Remove plugin mention from OBS-Studio

[MGThePro]

With wayland support now fully merged, it's not needed to install a plugin anymore

[deltragon]

I dont think the plugin mention can be removed yet - the merged PR was just for OBS itself to run on Wayland, not whether screen capturing works (if I understand correctly).
It seems that this PR would enable that (it is also linked on the plugin's readme), but it is not merged yet.
(Edit: Now that I look at it more I might be wrong about this - still, I would need to test it to be sure.)

[darkbasic]

#3338 is merged now.

[deltragon]

obsproject/obs-studio#4287 has been merged, which integrates the plugin into OBS itself. This should be available in OBS Studio 27, which means the plugin mention can be removed after that is released.

See also this blog entry from the author: https://feaneron.com/2021/03/30/obs-studio-on-wayland/

[mpsq]

Waiting for OBS 27 to be released before removing the mention to the plugin.

[rooiratel]

OBS 27 released: https://github.com/obsproject/obs-studio/releases/tag/27.0.0