R1:21021b55c4d2

Update configuring_file_domain.diviner's cloudflare link

Summary: [[ https://cloudflare.net | https://cloudflare.net ]] generates SSL certification error, and even if I click "ignore it", the page is 403 forbidden afterwards. Their domain has moved to .com, therefore update it to reflect this.

Test Plan:
Go to [[ https://secure.phabricator.com/book/phabricator/article/configuring_file_domain/ | Configuring a File Domain ]], click [[ https://cloudflare.net | CloudFlare]].
Then, apply the patch. Refresh…