Website: fix or clarify Proton version "default"

[fallenguru]

If I select "default" as the Proton version used, I'd expect the published report to show

• the whitelisted version [for games on the whitelist]; or else
• the most recent version available, based on the reported Steam version* [for all other games].
  *) The version set in "run other titles with" would be ideal, but that'd require uploading the Steam configuration as well.

Background: I submitted a report for Dungeon of the Endless yesterday with Proton version "default". The game is whitelisted, it uses the 3.16 branch (currently 3.16-9 on my machine), but the published report incorrectly shows 4.11-7.
So the report shows a version the game wasn't tested with and there's no way to tell apart (possibly off) "default" and manual "4.11-7" reports.

I'd suggest to improve the auto-selection of the default version (see above), display the version selected in the report preview so the user can double-check, and distinguish between manually selected versions and versions selected by default. As a stop-gap, adding an explanation on the submission page would work.

[dreamer]

Information about default Proton version for whitelisted games can be found e.g. on SteamDB: https://steamdb.info/app/891390/