Removing extra blank lines in docs that serve
no purpose, as well as some --- lines that also
are not needed.

Resolve "API support for group-level clusters"

Closes #55623

See merge request gitlab-org/gitlab-ce!30213

Remove unneeded trailing whitespace in lines in
/development /ci /api and /administration docs.

All code blocks should be surrounded by blank lines

Hard tabs do not follow general markdown guidelines
are were removed from the few docs that used them

Adds more friendly docs for GraphQl implementation

This is basically a copy of the API for project clusters.

Currently, the project visibility methods attribute description link to
the descriptions and options for visibility methods. The merge methods
attribute description doesn't should do the same.