owncloud.dev cleanup API - HTTP - LibreGraph (outdated and unmaintained subfolders)

When looking in owncloud.dev into section API - HTTP - LibreGraph, we find subfolders with static content that is outdated and unmaintained. These are the sections: Spaces, Users and Groups.

Post a discussion with @rhafer and @JanAckermann, we identified that the outdated content could be fully removed and replaced by a link in the libregraph page to the libgregraph api, see image below.

If any api content is missing, it could be added to the swagger page (@rhafer )