Nits on docs and repo

[magdalenafuentes]

Hey @ahnonay and @yiitozer thanks for creating this useful toolbox. Looks really good. I'll drop here some nits to follow JOSS guidelines and make the repo even clearer:

• JOSS recommends to add a statement of need in the documentation as well, so maybe it's worth to add not only the API description in the docs, but also a brief description and the statement in the index.
• I recommend you add a brief description in the about field of the GitHub repo as well as a link to the docs in the website field. It will make it quicker for people to get to the docs and also understand what the repo is about

openjournals/joss-reviews#3434

[meinardmueller]

Done. Thank you!