Update README - Add Sonic Forces pac files to list
Update README
- Add Sonic Forces pac files to list

- Fix error about when Mirage headers first appeared. (Idk why I wrote Rio 2016; I was just braindead I guess. Actually, not sure if there's any in London 2012. If so I'll have to update this again lol)
- Mention the specific versions of .model/.terrain-model files which are supported; right now only v5.0.
- Remove (none yet) from the line which links to stable builds

Radfordhound/HedgeLib,Radfordhound/HedgeLib