Getting models into the CellML repository

1. Guide to updating existing models You've downloaded a model, added an annotation or made a bugfix, and now you'd like to share it with the world.

2. Guide to adding new models You've created a new model, or made a CellML file for a model that doesn't have one yet, and now you'd like to share it with the world.

3. Getting a model into the "electrophysiology" section You've got a model in the repository, and now you want it to show up in the list of electrophysiology models.