Update cheatsheets

tldr/linux/protontricks

@@ -28,6 +28,10 @@ source: https://github.com/tldr-pages/tldr.git
 
 `protontricks -s {{game_name}}`
 
+- Run an executable in the proton environment of a specific game:
+
+`protontricks-launch --appid {{appid}} {{path/to/executable.exe}}`
+
 - Display help:
 
 `protontricks --help`