Update info about Overwatch Highlight saving on Linux

[ToasterUwU]

This is a followup on #156 in a way.

One of my friends that confirmed that this function used to be broken even with WEBM, no matter the machine or proton version (Check linked PR), made me aware that the WEBM method works again.

I just tried it and made another friend try it as well, and yes, it works again if using specifically WEBM.

I updated the section according to that, feel free to change or rephrase it however you want.