Merge branch 'ha-page' into 'master'

Update doc/administration/high_availability/README.md

See merge request gitlab-org/gitlab!29977

doc/administration/high_availability/README.md

@@ -2,6 +2,9 @@
 type: reference, concepts
 ---
 
-# High Availability
+The page have been deprecated, please see:
 
-This content has been moved to the [availability page](../availability/index.md).
+1. [Availability page](../availability/index.md)
+1. [Scaling page](../scaling/index.md)
+1. [Docs page for high availability](./gitlab.md)
+1. [High availability solutions page](https://about.gitlab.com/solutions/high-availability/)