NH-116007: update contributing and config doc

[xuan-cao-swi]

Description

Test (if applicable)

[tammy-baylis-swi]

Lgtm, it's definitely easier to read! I had some suggestions you can take or leave

[cheempz]

Wow, big revamp :) The thing i actually had in mind for this Jira task was actually much smaller task--now that it's pure Ruby, was thinking the CONTRIBUTING doc could be revamped so that dev workflow does not need to be in a container. Yes, to run the regression tests it would still spin up containers, but simply to make a change, run a specific test case, and do a local build should be achievable directly on MacOS now, correct?

[xuan-cao-swi]

now that it's pure Ruby, was thinking the CONTRIBUTING doc could be revamped so that dev workflow does not need to be in a container.

Oh right, yes, everything can run without container (although I still prefer container so it can enforce env isolation). I can add the additional context about running in host machine.

[cheempz]

Thanks @xuan-cao-swi . i left a bunch of suggestions for the CONFIGURATION page, it's a nice revamp but i do feel AI assisted content gets kind of verbose and we still need to check for correctness.

[cheempz]

LGTM, thanks for the revisit!