Refer to "3.0.0" in the release index

The release was tagged as "3.0.0" and is referred to like that
everywhere except one place in the release index.

Change-Id: I6f4f5a1c11c070e2775ec430ecb89b88cb9337a4
diff --git a/pages/site/releases/README.md b/pages/site/releases/README.md
index 5637906..39a8900 100644
--- a/pages/site/releases/README.md
+++ b/pages/site/releases/README.md
@@ -31,7 +31,7 @@
 
 * New core plugins: `delete-project`, `gitiles`, `plugin-manager` and `webhooks`.
 
-[Release notes for Gerrit 3.0](/3.0.md)
+[Release notes for Gerrit 3.0.0](/3.0.md)
 
 ## 2.16