Add warning about known issue in efm 5.0.

This adds a warning about a problem found in 5.0 with the efm create-standby command. This will be fixed for 5.1, which is why the note specifically calls out "5.0" in the note.

Author: EFM-Bobby

product_docs/docs/efm/5/07_using_efm_utility.mdx

@@ -97,6 +97,9 @@ The following example is generated by querying the status of a healthy cluster w
 
 ## efm create-standby
 
+!!!Note
+    Important information for version 5.0 only: If this command is run on a standby node (the local database is running and is being monitored), you must restart the agent after the command completes. There is a known issue that the agent can be left in an incorrect internal state. If this node is later promoted to primary and the database fails, there may not be a failover due to this state. This does not affect "Idle" nodes (where either the local database is not runnning or is not being monitored).
+
 `efm create-standby <cluster_name> [-prompt] [-slot <slot_name>]`
 
 Invoke the `efm create-standby` command to create a new standby database on this node. The local agent must be running and there must be a primary agent in the cluster. The command process will: