Decide How to Deal With Images at ReadTheDocs

We need to decide how to deal with images.

In the master branch of the documentation repo we didn't upload images to the repo. We can upload images to

• gitlab wiki and link them to the pages
• Earth Science's wiki
• repo (as done in the with-images branch, in commit 3c4035a2)

@bdepaula mentioned how other projects deal with this problem.