How to edit the documentation
The format is restructured text. Restructured text work a lot like markdown. However, the syntax is not the same. You can choose whatever editor you prefer to edit the .rst file. Once you edited them save them and remember to create a link to the file you want them to appear.
For example, if you want to add a file describing how_to_do_something to the index, create the how_to_do_something.rst file and then add ‘how_to_do_something’ to the index.rst file and it will appear in the HTML.
For a quick reference, here is a cheatsheet for .rst: https://github.com/ralsina/rst-cheatsheet/blob/master/rst-cheatsheet.rst
How to edit a Readme
The format of the README file for git is markdown. For a quick reference, here is a cheat-sheet summarizing how you can use it: https://guides.github.com/features/mastering-markdown/