doc: improve doc/markdown file organization coherence

* Updated cpp style guide file name and location and fixed links to
  this file.

* Updated collaborator guide file name and location and fixed links
  to this file.

* Updated documentation style guide file name and location and updated
  links referencing the file.

* Moved files to appropriate location and updated naming style for
  some of them.

Fixes: https://github.com/nodejs/node/issues/31741

PR-URL: https://github.com/nodejs/node/pull/31792


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>