Build the documentation for a given fork and branch

If you want to build the documentation on readthedocs for a work in progress in your own fork and a given branch, you should follow these steps:

1) On the first time

• connect to your readthedocs dashboard (create an account if you don't have one).
• import a project, using e.g. the GitHub URL. Name it "xdem-your_username" to avoid conflict with the main documentation.

2) For each new branch

• go to the "versions" tab, and select the branch for which you want to build the docs.
• click on "activate" and on the following window, also select "hidden" to avoid that other people accidentally fall on this version (instead of the main one). When clicking "save", it will automatically start the build.
• you can find the builds documentation in the "builds" tab and find the URL of that version. You can deactivate the build when you are done testing (or it will be deactivated when the branch is deleted).