Need a list of standards

This page https://apache.org/dev/standards/#standards-at-apache talks about standards in use at the ASF, and used to point to a list of implemented standards. That list no longer exists. We should either recreate it, with a way to keep it up to date, or perhaps remove the entire 'standards' folder if we are not in a position to give more information.

Start by inspecting the ASF standards page and the repository's standards folder, checking the broken reference and whether an existing source can support an up-to-date list. Done means choosing either a maintained replacement list or removal of the standards material, then updating the page consistently with that decision.

Written by the indexing model from the issue text.