Add note about resource filters (#19843)

* add note about resource filters

* Apply suggestions from code review

Co-authored-by: Ursula Chen <58821586+urseberry@users.noreply.github.com>

---------

Co-authored-by: Ursula Chen <58821586+urseberry@users.noreply.github.com>

Author: sarah-witt

vsphere/assets/configuration/spec.yaml

@@ -148,6 +148,7 @@ files:
                   resources do not have realtime metrics
           Note2: 'host' filters are ignored when collecting historical metrics as this resource does not have
                   historical metrics
+          Note3: If no filters are set for a resource type, all resources of that resource type are collected.
 
         value:
           example:

vsphere/datadog_checks/vsphere/data/conf.yaml.example

@@ -173,6 +173,7 @@ instances:
     ##         resources do not have realtime metrics
     ## Note2: 'host' filters are ignored when collecting historical metrics as this resource does not have
     ##         historical metrics
+    ## Note3: If no filters are set for a resource type, all resources of that resource type are collected.
     #
     # resource_filters:
     #   - resource: vm