[STEAM] Added docs and some tweaks for Linux Steam, also added a new env var for it

[ksco]

No description provided.

[LukeShortCloud]

This may have got lost in the resolved review, just wanted to mention:

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On a related note, I was thinking about updating this exact part, too.

We should probably mention that 8 GB of system memory (RAM and swap combined) is required. Then an example can be provided that a system with 6 GB of RAM will need a 2 GB swap file or zram.

I still haven't done any benchmarks with zram on Arm but the results on x86 are impressive if you know how to configure it right. My online notes are down so I can't currently link to it right now. :-(

[ksco]

Sounds good to me, feel free to update the new STEAM.md after this is merged! Also, I think it’s less and less necessary to maintain the README translations manually, I think it’s possible to provide a in-place translation via Google Translate or others, I’ll check later.