enable code highlighting for JS in readme

README.md

@@ -116,24 +116,28 @@ If you're using [TheThingsNetwork](https://www.thethingsnetwork.org/) you may wa
 
 Decoder:
 
-    function Decoder(bytes, port) {
+```javascript
+function Decoder(bytes, port) {
     var decoded = {};
     if (port === 1) {
       decoded.wifi = (bytes[0] << 8) | bytes[1];
       decoded.ble = (bytes[2] << 8) | bytes[3];
     }
     return decoded;
-    }
+}
+```
 
 Converter:
 
-    function Converter(decoded, port) {
+```javascript
+function Converter(decoded, port) {
   var converted = decoded;
   if (port === 1) {
     converted.pax = converted.ble + converted.wifi;
   }
   return converted;
-    }
+}
+```
 
 # Remote command set