Use the new links pointing to the GNOME Handbook website, as the wiki has been decommissioned.
Use the same structure as for the GNOME Shell and Mutter templates, as they have shown to work well.
This adds two new templates whenever an user decides to open a new issue: Bug.md is a template for new bugs Feature.md is a template for new features Both files came from the gnome-todo project. Fixes: #220