readme installation: added setup instructions for xlib

README.md

@@ -9,6 +9,18 @@ Optional: Install cpulimit to enable use of parameter `--cpu-limit`
 
     $ sudo apt-get install cpulimit
 
+Optional: Install xlib for python to enable extended controls:
+
+```{sh}
+$ sudo apt-get install python3-xlib
+```
+
+or
+
+```{sh}
+$ pip3 install --user xlib
+```
+
 ## Configuration
 
 ```yaml