[ux] Style Guide

[Giselle]

Hello,

I'm a student interested in this year's gsoc and I wanted to reach out about the style guide page(https://styleguide.torproject.org/getting-started/ ). It took me a while to figure out how to download the css file as it is a symlink. For usability purposes I think added documentation explaining how to pull the repo and the commands to deal with submodules would be helpful. On the style guide page it's probably more helpful to say that one needs to clone the repo rather than just download the file.   I'd be happy to update this on the styleguide page, but I'm not sure where this lives in your codebase. I can create a ReadMe file for https://gitlab.torproject.org/tpo/web/styleguide to explain the steps in setting up the repo. Let me know if you all think this is a good idea and if you have any more suggestions.

Thank you!

Giselle