Fix broken link in 3.8 release notes

The link was referring to a non-existing change 40014489 instead of
issue 40014489. The 3.6 release notes already contain the correct link.

Change-Id: I251eb2837cd0698e7541a58c6800ba9b6d453d99
diff --git a/pages/site/releases/3.8.md b/pages/site/releases/3.8.md
index 478536b..a325fb3 100644
--- a/pages/site/releases/3.8.md
+++ b/pages/site/releases/3.8.md
@@ -1278,7 +1278,7 @@
 
 * Documentation fixes
 
-  * [40014489](https://gerrit-review.googlesource.com/c/gerrit/+/40014489):
+  * [Issue 40014489](https://issues.gerritcodereview.com/issues/40014489):
   Announce / document that building with Java 8 is no longer supported
 
     Documents that building with Java 8 is no longer supported.