Disclaimer: this is not an official documentation from Tor. This is an independent list of resources run by Tor users to help each other to understand and deal with a problem that they have to deal with on a daily basis.
For official documentation from the Tor Project, visit https://www.torproject.org/

Need some documentation about CloudFlare? Here it is!

Most importantly: What can I do as a Tor user?

And also...

Of course, CloudFlare is not responsible for all blocks on Tor websites. Check out the list of websites that are blocked for other reasons and feel free to participate!

Oh, and have a look at La Quadrature du Net's aweseome fake CloudFlare captcha!

Contact @shiromarieke or marie dot gutbub at systemli dot org

French translation: https://github.com/shiromarieke/cloudflare_stuff/blob/master/cloudflare_fr.pdf