use import in README, #86

Author: grimmdude

README.md

@@ -154,7 +154,7 @@ The `Writer` class provides a few ways to output the file:
 Here's an example of how everyone's favorite song "Hot Cross Buns" could be written.  Note use of the mapping function passed as the second argument of `addEvent()`.  This can be used to apply specific properties to all events.  With some 
 street smarts you could also use it for programmatic crescendos and other property 'animation'.
 ```javascript
-const MidiWriter = require('midi-writer-js');
+import MidiWriter from 'midi-writer-js';
 
 const track = new MidiWriter.Track();