Document new database access permission in the 2.6 release notes

Change-Id: Ic6bf0e7990aea6bfab0c8e1adb7cabe343503678
diff --git a/ReleaseNotes/ReleaseNotes-2.6.txt b/ReleaseNotes/ReleaseNotes-2.6.txt
index ce8831f..70526e1 100644
--- a/ReleaseNotes/ReleaseNotes-2.6.txt
+++ b/ReleaseNotes/ReleaseNotes-2.6.txt
@@ -52,6 +52,11 @@
 * Remove Reviewer is a new permission.
 * Pushing a signed tag is a new permission.
 * Editing the topic name is a new permission.
+* Raw database access with the `gsql` command is a new global capability.
++
+Previously site administrators had this capability by default.  Now it has
+to be explicitly assigned, even for site administrators.
+
 * link:https://code.google.com/p/gerrit/issues/detail?id=1585[Issue 1585]:
 Viewing other users' draft changes is a new permission.