readme updated

README.md

@@ -9,6 +9,27 @@
 	- the board will go into bootloader mode and appear as USB thumb drive
 6. Copy the `soundcube-firmware.ino.uf2` file to the thumb drive and wait for the board to restart
 
+## config.txt
+
+Json formatted config file. For now only edge led color working.
+
+```
+{
+    "edge": {
+        "color":{
+            "r":50,
+            "g":0,
+            "b":0
+        }
+    }
+}
+```
+
+## click.wav (not played correctly)
+
+Put a file called `click.wav` (not longer than a few seconds) in the root of the SD card and it will play when you press a button.
+
+
 ## Code something yourself
 
 1. Download [Arduino IDE](https://www.arduino.cc/en/software/)