feat: Add as non-Steam game: Steamify in the Steam library, under the shortcut; controller works when started from Steam

README.md

@@ -30,6 +30,10 @@ Steam Machine.
 5. **Steamify shortcut** - "Steamify CachyOS" on the desktop and in the
    launcher opens the newest Steamify app, so you don't need the install
    command again. "Steamify Terminal" in the launcher opens the terminal menu.
+   With **Add as non-Steam game** (on by default) it's in your Steam library
+   too: started from Steam it gets your controller (a Steam Controller only
+   talks to Steam), in gaming mode as well. Steam closes for a moment while
+   it's added, so that's done from the desktop.
 6. **Update notifications** - on by default: a notification and a tray icon
    when there's a new Steamify, with Open Steamify and Skip this version. It
    never updates anything by itself