Update README.md

Author: mmorselli

README.md

@@ -1,6 +1,12 @@
 # Joy2OpenVR
 Interface to OpenVR Input Emulator to translate any Direct Input controllers commands into VR Controller commands, used, for example, to play VR Games with Cabela TopShot Elite equipped with a Vive Trackers
 
+usage: read comments in config.ini and configure. 
+
+To use alternative config files use:
+
+Joy2OpenVR.exe  filename.ini
+
 
 ![alt screenshot](https://github.com/mmorselli/Joy2OpenVR/blob/master/assets/screenshot.png)