Mkdocs setup

[Tobi-De]

Hi @simonprickett, hope you are doing great. I was wondering if you would be interested in a PR that would set up mkdocs for redisom, frankly there is not much to do, the docs is already there and working, but I think with something like mkdocs it would be easier to navigate. If you agree with the idea, I can start working on it. You can get an idea of what it looks like here