review comments from @shwstppr

Author: abh1sar

source/adminguide/extensions/limitations.rst

@@ -34,16 +34,12 @@ by adding custom actions in the scripts written for the built-in extensions.
 
    - Affinity Groups.
 
-   - Usage and Billing.
+   - Migrate Instance.
 
 **Actions which can be implemented using Custom Actions in built-in extensions:**
 
    - Reinstall Instance.
 
-   - Migrate Instance to another Host.
-
-   - Migrate Instance to another Storage.
-
    - Backup and Restore.
 
    - Recurring Snapshots.