Remove the technical github user as admin after configuring mirroring

Fix #386

.gitlab/issue_templates/New Official Project.md

@@ -93,3 +93,4 @@ If you want to add a new official project, here are some guidelines to follow:
 1. [ ] In the GitHub description of the mirrored project, append " (read-only mirror)" so that people know it's a mirror.
 1. [ ] Disable `Packages` and `Environments` from being shown on the main page.
 1. [ ] In the website field put the full url to the repository on our GitLab.
+½. [ ] Go to https://github.com/archlinux/my-example/settings/access and remove the GitHub account `archlinux-github`