cleanup contributing guide
@brandon_cook raising issue based on !1215 (comment 541487350) to help clean up git commands.
I don't particularly like this section: https://gitlab.com/NERSC/nersc.gitlab.io/-/blob/main/CONTRIBUTING.md#review-a-merge-request-from-a-private-fork and I don't see why we would have a private fork since this repo is public. Forks are public if repo is public.
Resolving merge conflicts section is important since this will happen quite often, so we briefly mention links to external docs so I think this section should remain.
I think this section https://gitlab.com/NERSC/nersc.gitlab.io/-/blob/main/CONTRIBUTING.md#edit-with-live-preview is not necessary because this is covered in WebGUI section which has links to WebGUI or IDE links to gitlab docs. The section for building docs mkdocs serve
can be moved to https://gitlab.com/NERSC/nersc.gitlab.io/-/blob/main/CONTRIBUTING.md#output-a-static-site which talks about mkdocs build
. This section can be expanded to state something like How to build documentation pages
The sync branches section is relevant because we can have NERSC staff and external users contribute by forking this repo and sending MR so before they start we don't want users starting a feature branch from main
that is not in sync. This will result in Merge Conflict and they will end up having to resolve bunch of conflicts.