Add python requirements file for the sphinx docs?

[mukul1992]

In my experience, installing the python package requirements for compiling the sphinx docs had to be done manually and was cumbersome. For instance, I believe the breathe package does not work with the most recent versions of sphinx. But there might be other dependency issues too while I hacked through it. Additionally some of the sphinx extensions are not installed automatically and had to be added manually while compiling.

I believe there is a practice to add a "requirements.txt" file in such cases for users to easily install the required dependencies. Should we add something like that, or are there other solutions? Of course this would be needed only for contributors to the documentation and not for regular users of the code.

If that seems like a good solution, I will attempt to prepare a minimal requirements file that is able to compile the docs successfully, as time permits.

[cgilet]

I think anything that lowers the barrier to adding documentation is a good idea! I'd be happy for you to do this.