[FAQ] Re organize the contents to clarify their release status

@moranegg @bchauvet here is a proposal, following a work session during which this point has been spotted:

https://gitlab.softwareheritage.org/outreach/swh-academy/swh-faq/-/blob/main/faq.md?ref_type=heads

Part of the contents are for the website and part of the others are for the docs (Sphinx). Need to clarify:

• which contents will be published where
• what is their current release status: WIP, validated, released?
• the process that should be followed?
• other topic to be added?