🆕 docs: Add new Antora site for docs.fp.o/community/

This commit installs a new Fedora Documentation site in this repository. It publishes a new Antora site to the docs.fp.o/community/ path, now making a dedicated portal for all things community in the Fedora Docs.

This is an initial commit and proof-of-concept, but I have specific motivations to move other content here eventually, like @isagordillo's Fedora intern hand-off information.

This site also needs to be built in the Fedora Documentation website builder repository; as of now, this site is not built in the public Fedora Docs website.