Add note about closing Grafana port 3370 by default on Docker deployments (#1129)

<!-- Explain the changes introduced in your PR -->
Add note about closing Grafana port 3370 by default on Docker
deployments, as per
sourcegraph/deploy-sourcegraph-docker#1204

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Co-authored-by: Maedah Batool <[email protected]>

Author: marcleblanc2

docs/admin/updates/docker_compose.mdx

@@ -11,6 +11,10 @@ For upgrade procedures or general info about sourcegraph versioning see the link
 >
 > ***If the notes indicate a patch release exists, target the highest one.***
 
+## v6.3 patch 1 
+
+- Grafana's port 3370 is no longer open by default for unauthenticated access for Docker Compose and Pure Docker deployments. Admins can still access Grafana by logging in to their Sourcegraph instance, navigating to the Site Admin page, then clicking Monitoring from the left navigation menu. If customers require port 3370 to be open, see [[PR 1204](https://github.com/sourcegraph/deploy-sourcegraph-docker/pull/1204/files)] for insight on how to add this port to their `docker-compose.override.yaml` file.
+
 ## v6.2.2553
 
 ### Known issues