Archiving the old edx-platform wiki on GitHub

The edx-platform repo on GitHub had a wiki that we have not used in years. There were about 50 pages, and the last substantial updates were from 2015/2016. Most of the information is out of date and documented better elsewhere, although it’s been occasionally useful when debugging very old code.

We are finally turning off that wiki, and we have archived its contents as openedx-unsupported/edx-platform-wiki.

This does not affect the Open edX Confluence Wiki, which we still use on a day-to-day basis.