Starting a docs index landing page.

Keep this PR open until we are satisfied with the content on it. We
don't need to start worrying about the design or anything, just as is
it's not even remotly done. For example the links all have 'docs/' in
front of them.

At some point the Markdown files in docs/ should really have a class
made for them to help deal with them. But we can talk more about that
later.

This commit also fixes problems with trailing slashes in routes. Your welcome
in advance.