Link vSphere billing docs to integration docs (#19241)

* link vSphere billing docs

* Update vsphere/README.md

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/README.md

@@ -97,7 +97,11 @@ See [service_checks.json][12] for a list of service checks provided by this inte
 
 You can limit the number of VMs pulled in with the VMWare integration using the `vsphere.d/conf.yaml` file. See the `resource_filters` parameter section in the [sample vsphere.d/conf.yaml][4].
 
-### Monitoring vSphere Tanzu Kubernetes Grid (TKG)
+## Billing
+
+- [vSphere Integration Billing][17]
+
+## Monitoring vSphere Tanzu Kubernetes Grid (TKG)
 
 The Datadog vSphere integration collects metrics and events from your [TKG][13] VMs and control plane VMs automatically. To collect more granular information about your TKG cluster, including container-, pod-, and node-level metrics, you can install the [Datadog Agent][14] on your cluster. See the [distribution documentation][15] for example configuration files specific to TKG.
 
@@ -121,3 +125,4 @@ The Datadog vSphere integration collects metrics and events from your [TKG][13]
 [14]: https://docs.datadoghq.com/containers/kubernetes/installation/?tab=operator
 [15]: https://docs.datadoghq.com/containers/kubernetes/distributions/?tab=operator#TKG
 [16]: https://www.datadoghq.com/blog/unified-vsphere-app-monitoring-datadog/#auto-discovery-across-vm-and-app-layers
+[17]: https://docs.datadoghq.com/account_management/billing/vsphere