Clarify that starred-changes ref is not needed on slaves

When using the replication plugin to push to a Gerrit slave
or to a standard Git repository, refs/starred-changes/* is not
needed in the replication.config.

Change-Id: Ia77da5a0a8b0247470507bf28680117801c441d3

src/main/resources/Documentation/about.md

diff --git a/src/main/resources/Documentation/about.md b/src/main/resources/Documentation/about.md
index 69a371b..adb8d4c 100644
--- a/src/main/resources/Documentation/about.md
+++ b/src/main/resources/Documentation/about.md
@@ -24,7 +24,7 @@
 
 * `refs/users/*` (user branches)
 * `refs/meta/external-ids` (external IDs)
-* `refs/starred-changes/*` (star labels)
+* `refs/starred-changes/*` (star labels, not needed for Gerrit slaves)
 * `refs/sequences/accounts` (account sequence numbers, not needed for Gerrit
   slaves)