Clean up README file.

README.md

@@ -1,14 +1,16 @@
 Used to load and save PO files.
 
-    var po = require('node-po')  
-      , fs = require('fs')
+```js
+var PO = require('node-po');
 
-    po.load('text.po', function(_po){
-      console.log(_po.headers);
-      console.log(_po.items);
+PO.load('text.po', function (err, po) {
+    // Handle err if needed
+    console.log(po.headers);
+    console.log(po.items);
   
-      _po.save('copy.po', function(){
+    po.save('copy.po', function (err) {
+        // Handle err if needed
         console.log('We copied a PO file for no reason!');
     });
 });
-    
+```