This started as an attempt to document variable naming conventions to address #22156 and well trying to put a table into a bullet list didn't work well and that had me thinking that a bullet list is the wrong structure when tables are involved so 😅 this PR:

• moves a lot of text out of notes and turns it into the preambles they were functionally acting as
• consolidates the contributor checklists sections, mostly by removing content and instead linking out to where it's discussed/described
• better distinguish contributor content checklist from github checklist
• move the checklist .css into the mpl.css file
• moved info on updating a pull request to the workflow-> as with [Doc]: Move Automated Tests section to workflow docs #26998, this is to better scope the PR guidelines doc to being about the content of the PR and the git workflow doc to be about git/github specific workflow.
• moved bulkier bullet points into coding guidelines as subsections to avoid having two coding guides b/c [Doc]: consolidate coding guidelines  #26095
• moved all the what's new/API changes stuff out to the coding guidelines too and reworked that section a drop b/c [Doc]: consolidate coding guidelines  #26095
  • the changes to the API/What's new readmes just moves the duplicated part to the bottom so that it can get cropped in the include.
  • I would like to also remove the very large item bulleted lists here (I think most of them are really tables), but I'd like to move all the "new/changed/deprecated API" info out into its own page because it is a lot of content.

While it may not seem like it, I have tried to avoid rewording/rewriting except to remove redundancy. In particularly, I'm trying to remove duplicate sets of detailed instructions b/c I think that creates space for deviation in those instructions/confusion.

Next Steps

I think merging this should be good enough to close #26095 cause it'll at least put everything in one place (mostly). I don't want to overwhelm this PR w/ changes since it's already doing a lot more than I planned, but once this is merged I'd like to clean up the code section of the policy and guidelines page so that it can just be a TOC. To do so, I think a sensible swapping would be to

1. move the contents of code_guidelines in contribute into the file called code guidelines
2. move the API changes content into its own file
3. move the pull request checklists out of coding_guidelines into their own file:
   • alt: contributor checklist -> coding guide, maintainer checklist -> pr triage file
4. move the information that has to do with pull request triage into a pull_request_triage file and move that under triage

Basically proposing that the code section of policies & guidelines changes:

and the triage section changes to

or the pull request triage document gets moved to maintenance, but technically I think anyone w/ triage rights can do most of the triage stuff discussed in the pull request guide.