make clear in docs that we are agnostic to the git cloud hosting service

[orbeckst]

@hejamu mentioned that our docs for adding a MDAKit were not clear on the fact that the source code can also be held in a GitLab repo and that it does not have to be GitHub.

The docs/template file should be changed yo make this clear.

[IAlibay]

tbh we never really tested it - we probably should so we have suitable caveats in place if things don't work