Add documentation

[m-o-e]

Please

• Explain how each protection works and the corner cases
• Explain how to correctly implement each protection in a Rack/Sinatra app
• Explain how to test each protection in a live app (to ensure they are properly enabled)

[m-o-e]

Ha! ;)

To clarify what was going on: I closed my request after realizing that the code is actually quite well-documented and easy to follow. Thus personally I don't need the docs anymore, but I still think new users would benefit from some guidance. Especially with regard to the critical protections that are disabled by default (CSRF!), which is imho not obvious from the current README.

[rkh]

There are CSRF protections that are not disabled by default. We need to make docs more accessible and actually give more examples.

[zzak]

I would agree there is serious lack of examples, but the docs should be accessible now as of closing #161.

I'll close this now and open up a new ticket upstream to explain the situation -- which hopefully will gain more traction than this repo.