README: use new bug template

This will prefill all the settings so users can report things better.

Change-Id: I1ccfd3a2c6835489db1fd2ba71aee39058ffe597
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/256872
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: David Pursehouse <dpursehouse@collab.net>

README.md

@@ -50,6 +50,6 @@ $ chmod a+rx ~/.bin/repo
 ```
 
 
-[new-bug]: https://bugs.chromium.org/p/gerrit/issues/entry?components=repo
+[new-bug]: https://bugs.chromium.org/p/gerrit/issues/entry?template=Repo+tool+issue
 [issue tracker]: https://bugs.chromium.org/p/gerrit/issues/list?q=component:repo
 [repo-discuss]: https://groups.google.com/forum/#!forum/repo-discuss