docs(issue-1215): restructure top level docs

[chrisk-7777]

Related Issues

Fixes #1215

Summary

This restructures the docs to support the discussion here and the related issue

This PR is an initial PR to get an approximate, but decent, structure in place for the new documentation site. There will be room to iterate on it in the following documentation-tagged issues. ie. this is not the final stage of updating the docs.

• I didn't split out the recipes. I'm not sure yet if there is value there, once I go through recipes as part of [documentation update] Individual page audit #1220 there may be room to split.
• This PR doesn't directly address any doc content yet, it is mostly renaming and reordering.
• There are some stub pages to be filled out in the following issues

Check List

• yarn run prettier for formatting code and docs

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 6d69c67:

Sandbox	Source
React	Configuration
React Typescript	Configuration
React Browserify	Configuration
React Snowpack	Configuration
React Parcel	Configuration

[dai-shi]

Looks good for a start. Thanks!