Adds npm install diceware to README

README.md

@@ -4,6 +4,12 @@
 
 It's worth noting that [it's not recommended](http://world.std.com/~reinhold/dicewarefaq.html#electronic) to use a computer to generate a Diceware phrase. If you want to generate passphrases in node.js, check out [https://github.com/shimaore/password](https://github.com/shimaore/password) instead.
 
+```
+    npm install diceware
+```
+
+```
     diceware = require('diceware');
     console.log(diceware());   // by default generates a 5 word phrase
-    console.log(diceware(10)); // but number of words can optionally be specified
+    console.log(diceware(10)); // but number of words can optionally be specified
+```