Add some gamemode optimization configs to Wiki page

[PhoenixEmik]

It's good to make an optimization while running osu! in windowed mode on KDE, which can be added to https://github.com/NelloKudo/osu-winello/wiki/(Possibly)-optimize-your-game:-Gamemode
Adding the following configs to /etc/gamemode.ini will disable compositing automatically when launching osu! (or any other programs) via gamemode. And it will enable compositing after exiting osu!.

[custom]
start=kdialog --title 'Gamemode' --passivepopup 'Started' 2
start=qdbus org.kde.KWin /Compositor org.kde.kwin.Compositing.suspend
end=kdialog --title 'Gamemode' --passivepopup 'Stopped' 2
end=qdbus org.kde.KWin /Compositor org.kde.kwin.Compositing.resume

On some distros (eg. openSUSE Tumbleweed), use qdbus-qt5 instead of qdbus.

[custom]
start=kdialog --title 'Gamemode' --passivepopup 'Started' 2
start=qdbus-qt5 org.kde.KWin /Compositor org.kde.kwin.Compositing.suspend
end=kdialog --title 'Gamemode' --passivepopup 'Stopped' 2
end=qdbus-qt5 org.kde.KWin /Compositor org.kde.kwin.Compositing.resume

[NelloKudo]

I guess I could but I provide the same instructions for KDE at least in the Compositing page of the wiki, installing Autocomposer should do the same job.

Still providing more info for gamemode sounds good, I guess I’ll do it when I’m free ;)

[PhoenixEmik]

Autocomposer only works when a fullscreen application is running, it does nothing with windowed mode osu!. That's the reason that I use gamemode.
BTW disable desktop effects option in Lutris is broken so that doesn't help. lutris/lutris#2596

[tloc241]

omg, this post actually fixing my suttering issue while using gamemode 0_0
(didn't expect it to work bcs my DE is lxqt not kde)

[PhoenixEmik]

The qdbus method has been removed in KDE Plasma 6. And the popular KWin script Autocomposer is also broken now.
The hotkey for toggling compositing still works instead:

xdotool key shift+alt+F12   # the F has to be uppercase