Add a link for the issues that have a Change-Id but not marked Fixed

Change-Id: I13986be3ed8bccff230cf7e00d37318a05246993
Reviewed-on: https://chromium-review.googlesource.com/1107119Reviewed-by: Chris Palmer <palmer@chromium.org>
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568636}

docs/security/sheriff.md

@@ -67,6 +67,7 @@ transitions to **Fixed**.
 close. Make sure to read bug comments where developer might point out that it
 needs more CLs, et c. Wait 24 hours before closing ClusterFuzz bugs, to give
 ClusterFuzz a chance to close it automatically.
+  * [Starting point](https://bugs.chromium.org/p/chromium/issues/list?can=2&q=Type%3D%22Bug-Security%22+%22Change-Id:%22)
 * Look at open security bug reports and check that progress is occurring.
 * Generally keep an eye on all bug traffic in case anything needs action or
 replying to.