chore(niri): add screenshot keybind

Changed files
+1
.config
niri
+1
.config/niri/config.kdl
···
Mod+W { toggle-column-tabbed-display; }
Print { screenshot; }
Ctrl+Print { screenshot-screen; }
Alt+Print { screenshot-window; }
···
Mod+W { toggle-column-tabbed-display; }
+
Mod+P {screenshot;}
Print { screenshot; }
Ctrl+Print { screenshot-screen; }
Alt+Print { screenshot-window; }