[reference] Fix external links (#686)

In the migration tool, external URLs that contained `.html` were
incorrectly modified to use `.md`.

To (attempt) to fix these links:

1. I ran a script to find URLs that started with `http` (i.e. is not an
internal or cross-repo link) and included `.md` somewhere in the URL.
2. Then I ran all the resulting URLs through an external link-checker.
i. If I got a [`200` status
code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/200)
back, I didn't do anything to the link.
ii. If I got a [`404` status
code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/404)
back, I swapped out the `.md` with `.html`.
3. I reran the link-checker to make sure all the updated links were now
returning `200`.

reference/glossary/index.md

@@ -537,7 +537,7 @@ $$$glossary-no-op$$$ no-op
 
 $$$glossary-node$$$ node
 :   1. A single {{es}} server. One or more nodes can form a [cluster](/reference/glossary/index.md#glossary-cluster). See [Clusters, nodes, and shards](/deploy-manage/production-guidance/getting-ready-for-production-elasticsearch.md).
-2. In {{eck}}, it can refer to either an [Elasticsearch Node](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-node.md) or a [Kubernetes Node](https://kubernetes.io/docs/concepts/architecture/nodes/) depending on the context. ECK maps an Elasticsearch node to a Kubernetes Pod which can get scheduled onto any available Kubernetes node that can satisfy the [resource requirements](/deploy-manage/deploy/cloud-on-k8s/manage-compute-resources.md) and [node constraints](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/) defined in the [pod template](/deploy-manage/deploy/cloud-on-k8s/customize-pods.md).
+2. In {{eck}}, it can refer to either an [Elasticsearch Node](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-node.html) or a [Kubernetes Node](https://kubernetes.io/docs/concepts/architecture/nodes/) depending on the context. ECK maps an Elasticsearch node to a Kubernetes Pod which can get scheduled onto any available Kubernetes node that can satisfy the [resource requirements](/deploy-manage/deploy/cloud-on-k8s/manage-compute-resources.md) and [node constraints](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/) defined in the [pod template](/deploy-manage/deploy/cloud-on-k8s/customize-pods.md).
 
 $$$NodeSet$$$NodeSet
 :   A set of Elasticsearch nodes that share the same Elasticsearch configuration and a Kubernetes Pod template. Multiple NodeSets can be defined in the Elasticsearch CRD to achieve a cluster topology consisting of groups of Elasticsearch nodes with different node roles, resource requirements and hardware configurations (Kubernetes node constraints).

reference/ingestion-tools/fleet/elastic-agent-inputs-list.md

@@ -41,7 +41,7 @@ When you [configure inputs](/reference/ingestion-tools/fleet/elastic-agent-input
 | `haproxy/metrics` | Collects stats from [HAProxy](http://www.haproxy.org/). It supports collection from TCP sockets, UNIX sockets, or HTTP with or without basic authentication. | [HAProxy module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-overview.md) ({{metricbeat}} docs) |
 | `http/metrics` | Used to call arbitrary HTTP endpoints for which a dedicated Metricbeat module is not available. | [HTTP module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-http.md) ({{metricbeat}} docs) |
 | `iis/metrics` | Periodically retrieve IIS web server related metrics. | [IIS module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-iis.md) ({{metricbeat}} docs) |
-| `jolokia/metrics` | Collects metrics from [Jolokia agents](https://jolokia.org/reference/html/agents.md) running on a target JMX server or dedicated proxy server. | [Jolokia module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-jolokia.md) ({{metricbeat}} docs) |
+| `jolokia/metrics` | Collects metrics from [Jolokia agents](https://jolokia.org/reference/html/agents.html) running on a target JMX server or dedicated proxy server. | [Jolokia module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-jolokia.md) ({{metricbeat}} docs) |
 | `kafka/metrics` | Collects metrics from the [Apache Kafka](https://kafka.apache.org/intro) event streaming platform. | [Kafka module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-kafka.md) ({{metricbeat}} docs) |
 | `kibana/metrics` | Collects metrics about {{Kibana}}. | [{{kib}} module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-kibana.md) ({{metricbeat}} docs) |
 | `kubernetes/metrics` | As one of the main pieces provided for Kubernetes monitoring, this module is capable of fetching metrics from several components. | [Kubernetes module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-kubernetes.md) ({{metricbeat}} docs) |
@@ -56,15 +56,15 @@ When you [configure inputs](/reference/ingestion-tools/fleet/elastic-agent-input
 | `oracle/metrics` | The [Oracle](https://www.oracle.com/) module for Metricbeat. It is under active development with feedback from the community. A single Metricset for Tablespace monitoring is added so the community can start gathering metrics from their nodes and contributing to the module. | [Oracle module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-oracle.md) ({{metricbeat}} docs) |
 | `postgresql/metrics` | Periodically fetches metrics from [PostgreSQL](https://www.postgresql.org/) servers. | [PostgresSQL module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-postgresql.md) ({{metricbeat}} docs) |
 | `prometheus/metrics` | Periodically scrapes metrics from [Prometheus exporters](https://prometheus.io/docs/instrumenting/exporters/). | [Prometheus module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-prometheus.md) ({{metricbeat}} docs) |
-| `rabbitmq/metrics` | Uses the [HTTP API](http://www.rabbitmq.com/management.md) created by the management plugin to collect RabbitMQ metrics. | [RabbitMQ module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-rabbitmq.md) ({{metricbeat}} docs) |
+| `rabbitmq/metrics` | Uses the [HTTP API](http://www.rabbitmq.com/management.html) created by the management plugin to collect RabbitMQ metrics. | [RabbitMQ module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-rabbitmq.md) ({{metricbeat}} docs) |
 | `redis/metrics` | Periodically fetches metrics from [Redis](http://redis.io/) servers. | [Redis module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-redis.md) ({{metricbeat}} docs) |
 | `sql/metrics` | Allows you to execute custom queries against an SQL database and store the results in {{es}}. | [SQL module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-sql.md) ({{metricbeat}} docs) |
 | `stan/metrics` | Uses [STAN monitoring server APIs](https://github.com/nats-io/nats-streaming-server/blob/master/server/monitor.go) to collect metrics. | [Stan module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-stan.md) ({{metricbeat}} docs) |
 | `statsd/metrics` | Spawns a UDP server and listens for metrics in StatsD compatible format. | [Statsd module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-statsd.md) ({{metricbeat}} docs) |
 | `syncgateway/metrics` | [beta] Monitor a Sync Gateway instance by using its REST API. | [SyncGateway module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-syncgateway.md) ({{metricbeat}} docs) |
 | `system/metrics` | Allows you to monitor your server metrics, including CPU, load, memory, network, processes, sockets, filesystem, fsstat, uptime, and more. | [System module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-system.md) ({{metricbeat}} docs) |
 | `traefik/metrics` | Periodically fetches metrics from a [Traefik](https://traefik.io/) instance. | [Traefik module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-traefik.md) ({{metricbeat}} docs) |
-| `uwsgi/metrics` | By default, collects the uWSGI stats metricset, using [StatsServer](https://uwsgi-docs.readthedocs.io/en/latest/StatsServer.md). | [uWSGI module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-uwsgi.md) ({{metricbeat}} docs) |
+| `uwsgi/metrics` | By default, collects the uWSGI stats metricset, using [StatsServer](https://uwsgi-docs.readthedocs.io/en/latest/StatsServer.html). | [uWSGI module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-uwsgi.md) ({{metricbeat}} docs) |
 | `vsphere/metrics` | Uses the [Govmomi](https://github.com/vmware/govmomi) library to collect metrics from any Vmware SDK URL (ESXi/VCenter). | [vSphere module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-vsphere.md) ({{metricbeat}} docs) |
 | `windows/metrics` | Collects metrics from Windows systems. | [Windows module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-windows.md) ({{metricbeat}} docs) |
 | `zookeeper/metrics` | Fetches statistics from the ZooKeeper service. | [ZooKeeper module](asciidocalypse://docs/beats/docs/reference/metricbeat/metricbeat-module-zookeeper.md) ({{metricbeat}} docs) |