Move restructure proposal into github repo

[adamblanchard]

Context

Right now, the current source of truth for the restructure is in here https://docs.google.com/document/d/151MLm-8WA6jSk0-9JhBTuG1xZ9Fo9HRLplJx6Bhps6A/edit?tab=t.0

Javascript/node is currently under discussion here #29

Description

This ticket should move the proposal into github, so all the plans and decisions live in the same place (rather than on a separate google doc)

This does NOT mean to actually implement any of the changes described in the proposal. This first pass should simply link to legacy content, leave stubs for content we need to add, and a todo list for any current known changes.

[adamblanchard]

Things left in this task (thinking out loud)

1. Move descriptions out of the doc into the repo so we only have to refer to github from now on
2. Move lists of required changes, optional changes, and decisions still to be made into issues