templates/rebase: add -v to koji untag-build

This will give you some status updates to the screen while it's running.
Otherwise there's not much feedback to the user and you aren't sure if
it's working or not.

.github/ISSUE_TEMPLATE/rebase.md

@@ -140,7 +140,7 @@ If there are any RPMs signed by the old key they'll need to be investigated. May
 
 ```
 # use xargs so we don't exhaust bash string limit
-cat untaglist | xargs -L50 koji untag-build coreos-pool
+cat untaglist | xargs -L50 koji untag-build -v coreos-pool
 ```
 
 - [ ] Now that untagging is done, give a heads up to rpm-ostree developers that N-2 packages have been untagged and that they may need to update their CI compose tests to freeze on a newer FCOS commit.