Add changelogs to proton in steamlibrary activity/news

[polluxau]

Feature Request

I confirm:

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

Description

I would like to see valve putting their changelogs for different proton version releases in the steamlibrary activity section like what other games or software do on steam

Like this for example from deadlock :)

Justification

I feel like most users will not go to the changelog on GitHub for proton as lots of new users don't know about the changes that are happening, it would bring a lot more clarity and understanding for new Linux gamers or steamdeck users about the changes, so let's say a game starts working on experimental they will know about it easier because of it being in that news section for whatever proton version it is without needing to go to GitHub to find what changed

Risks

I dont think it would bring any risks

[kisak-valve]

Partial duplicate of https://github.com/ValveSoftware/steam-for-linux/issues/11290.