Apparently the docs changed so the anchor is broken (and contributors
are confused). Also the docs now says that Container Registry is enabled
by default. I assume this must be a recent change which is not available
yet in GNOME's Gitlab instance. So we must ask people to do the opposite
of what the docs says.
Add a note asking bug reporters to test with the latest stable version
of GIMP or with dev code (not with old stable versions).
Also add some labels on bug reports and feature requests.
We realize that gitlab doesn't encourage people to give base information
as software version or operating system.
Issue templates are not perfect but better than nothing.
