Document ssh command descriptions in the 2.6 release notes

Change-Id: I943a30aabbdf82d5a13a19bae133463fdab1f8d5
diff --git a/ReleaseNotes/ReleaseNotes-2.6.txt b/ReleaseNotes/ReleaseNotes-2.6.txt
index 4868e43..d3a67ba 100644
--- a/ReleaseNotes/ReleaseNotes-2.6.txt
+++ b/ReleaseNotes/ReleaseNotes-2.6.txt
@@ -62,6 +62,11 @@
 
 SSH
 ~~~
+* Descriptions are added to ssh commands.
++
+If `gerrit` is called without arguments, it will now show a list of available
+commands with their descriptions.
+
 * `create-account --http-password` enables setting/resetting the
   HTTP password of role accounts, for Git or JSON API access.