Update 'Documentation' section in Gerrit 2.6 release notes

Change-Id: If0115e765bfd261905d98baa73dbea4e92dd8269
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/Documentation/dev-release.txt b/Documentation/dev-release.txt
index 0f87124..d429a1cc 100644
--- a/Documentation/dev-release.txt
+++ b/Documentation/dev-release.txt
@@ -23,6 +23,7 @@
 type of release you want to make (`stable-fix`, `stable`, `RC0`,
 `RC1`...).
 
+[[stable]]
 Stable
 ~~~~~~
 
@@ -62,6 +63,7 @@
 objectives are met
 
 
+[[security]]
 Security-Fix
 ~~~~~~~~~~~~