Clarify process of adding projects

[xloem]

Just to confirm:

To use this, I think we need to either submit a PR to you, or run our own web server, and add the project to the ganarchy sources?
But no changes need be made to the actual project that's added?

[SoniEx2]

You need to create a project commit, like so: ganarchy/GAnarchy@385e734

The important part is the commit message. The changes don't matter (in particular, the commit can be empty). Then just add the project to a config: either submit a PR here adding the project to the config, or run your own web server with the appropriate changes.