Feature Request, Kinda

I confirm:

• [x] that I haven't found another request for this feature.
• [x] that I have checked whether there are updates for my system available that
  contain this feature already.

Description

The PREREQS.md that was linked to in many places, including the Steam Play FAQ, returns 404

Justification [optional]

It was useful to have, I think, I have no idea what was there since its gone.

Risks [optional]

References [optional] None that I could find