Reorganize OLX Docs into Diataxis Framework

[jswope00]

The OLX docs have been migrated from legacy docs to Open edX Docs as part of this PR: #819

They should still be reorganized into sensible Diataxis framework. See these docs:
Diatixis Definitions: https://docs.openedx.org/en/latest/documentors/concepts/content_types.html
A holistic migration checklist (including setting the correct diataxis tag): https://docs.openedx.org/en/latest/documentors/references/doc_checklist.html

This could mean merging docs together when they serve the same diataxis purpose, splitting docs when they serve different purposes, and maintaining sensible navigation and titles through those changes.

[sarina]

OLX documents are linked to in myriad places. For redirect purposes it might be nice to not fully delete a given page (including renaming) but instead leave the page as a stub with just a seealso to the diataxis pages.

The pages can be included in a :hidden: toctree.