Fix dangling link in documentation to gerrit's commentlink documentation

Change-Id: I31558ed950c8b025fb31438982a34aa674cb01ef

src/main/resources/Documentation/config-common.md

diff --git a/src/main/resources/Documentation/config-common.md b/src/main/resources/Documentation/config-common.md
index 13720b4..97a7464 100644
--- a/src/main/resources/Documentation/config-common.md
+++ b/src/main/resources/Documentation/config-common.md
@@ -51,6 +51,8 @@
 :	 Bug-ids are liked when found in the git commit message, no warning is
 	 displayed otherwise.
 
+[upstream-comment-link-doc]: ../../../Documentation/config-gerrit.html#commentlink
+
 
 
 [enabling-its-integration]: #enabling-its-integration