[docs] RTD `Edit on GitHub` link points to 404 URL

[jono3030]

The Edit on GitHub link on our RTD page points to the wrong URL for the file it's supposed to be referencing. RTD misses the docs part of the URL.

Example:

https://github.com/AICONSlab/MIRACL/blob/master/index.rst

should actually be:

https://github.com/AICONSlab/MIRACL/blob/master/docs/index.rst

I suspect this is due to a missing conf_py_path entry in the html_context dictionary of our RTD's conf.py in the repo. This is caused by our config file not being at the root directory of the repo but in the docs folder instead.