Add jsonpointer.compile to README

Author: marcbachmann

README.md

@@ -3,17 +3,24 @@
 This is an implementation of [JSON Pointer](http://tools.ietf.org/html/draft-ietf-appsawg-json-pointer-08).
 
 ## Usage
-
-    var jsonpointer = require("jsonpointer");
-    var obj = { foo: 1, bar: { baz: 2}, qux: [3, 4, 5]};
-    var one = jsonpointer.get(obj, "/foo");
-    var two = jsonpointer.get(obj, "/bar/baz");
-    var three = jsonpointer.get(obj, "/qux/0");
-    var four = jsonpointer.get(obj, "/qux/1");
-    var five = jsonpointer.get(obj, "/qux/2");
-    var notfound = jsonpointer.get(obj, "/quo"); // returns null
-
-    jsonpointer.set(obj, "/foo", 6); // obj.foo = 6;
+```javascript
+var jsonpointer = require('jsonpointer');
+var obj = { foo: 1, bar: { baz: 2}, qux: [3, 4, 5]};
+
+jsonpointer.get(obj, '/foo');     // returns 1
+jsonpointer.get(obj, '/bar/baz'); // returns 2
+jsonpointer.get(obj, '/qux/0');   // returns 3
+jsonpointer.get(obj, '/qux/1');   // returns 4
+jsonpointer.get(obj, '/qux/2');   // returns 5
+jsonpointer.get(obj, '/quo');     // returns null
+
+jsonpointer.set(obj, '/foo', 6);  // sets obj.foo = 6;
+jsonpointer.set(obj, '/qux/-', 6) // sets obj.qux = [3, 4, 5, 6]
+
+pointer = jsonpointer.compile('/foo')
+pointer.get(obj)    // returns 1
+pointer.set(obj, 1) // sets obj.foo = 1
+```
 
 ## Testing