Update README with JSON Patch example

Also, replace the remaining tabs with spaces.

README.md

@@ -1,43 +1,46 @@
-# Warlock!
+# Warlock
 
-## Wat
+Build self-validating python objects using JSON schemas.
 
-Build self-validating python objects using JSON schemas
+1) Create your schema
 
-## How
-
-1) Build your schema
-
-	>>> schema = {
-	    'name': 'Country',
-	    'properties': {
-	        'name': {'type': 'string'},
-	        'abbreviation': {'type': 'string'},
-	    },
-	    'additionalProperties': False,
-	}
+    >>> schema = {
+        'name': 'Country',
+        'properties': {
+            'name': {'type': 'string'},
+            'abbreviation': {'type': 'string'},
+            'population': {'type': 'integer'},
+        },
+        'additionalProperties': False,
+    }
 
 2) Create a model
 
     >>> import warlock
-	>>> Country = warlock.model_factory(schema)
+    >>> Country = warlock.model_factory(schema)
 
 3) Create an object using your model
 
-	>>> sweden = Country(name='Sweden', abbreviation='SE')
+    >>> sweden = Country(name='Sweden', abbreviation='SE')
 
-4) Let the object validate itself!
+4) Let the object validate itself
 
     >>> sweden.name = 5
     Traceback (most recent call last):
-	  File "<stdin>", line 1, in <module>
+      File "<stdin>", line 1, in <module>
       File "warlock/core.py", line 53, in __setattr__
         raise InvalidOperation(msg)
     warlock.core.InvalidOperation: Unable to set 'name' to '5'
 
     >>> sweden.overlord = 'Bears'
     Traceback (most recent call last):
-	  File "<stdin>", line 1, in <module>
+      File "<stdin>", line 1, in <module>
       File "warlock/core.py", line 53, in __setattr__
         raise InvalidOperation(msg)
     warlock.core.InvalidOperation: Unable to set 'overlord' to 'Bears'
+
+5) Generate a [JSON Patch document](http://tools.ietf.org/html/draft-ietf-appsawg-json-patch) to track changes
+
+    >>> sweden.population=9453000
+    >>> sweden.patch
+    '[{"path": "/population", "value": 9453000, "op": "add"}]'