Restructured gitlab pages for docs
This PR restructures the published documentation, to make the pages easier to navigate (in principle). The main points are:
- user docs are now top-level at https://docs.ligo.org/nds/nds2-client/
- Administrator and Developer docs are now at
- The SWIG bindings docs are in the same structure with an extra 'swig' component:
- docs still build for every commit, but the
pagesjob that published the documentation only runs for tags, so no 'Release' vs 'Dev' builds.
One thing that would probably be useful, if this merge is accepted, is to add a reference to the 'swig' documentation from the top-level client docs pages, and vice-versa.