New template that can extract all the necessary files from the AppImage itself, usage:
am -t $APPNAME
then select the template number 7, "APPIMAGE FROM GITHUB.COM (ALWAYS UPDATABLE)".
All you have to do is add the repository's name.
The template in question is available at this link, others will be added in minor releases in order to simplify the work of developers who want to share their AppImage packages on this database.