Now that CA supports plugins, there is a separate xml schema for them which is basically a trimmed down docker template.   There is no naming convention for the actual template files, but you really should avoid any punctuation, quotation marks, etc that could mess up the appfeed.   After creating the templates, you will need to create a new gitHub repository (a new one because if there are any other .xml files within an existing repository, the appfeed will wind up trying to