docs/file_domain: Update cloudflare spelling and URLs
Summary:
Cloudflare now spell themselves as Cloudflare.[1]
[1]: https://www.cloudflare.com/trademark/
Signed-off-by: Yongmin Hong <revi@omglol.email>
Test Plan: Read the Docs ™️.
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D25616