Added class arguments example for Python 3

UPGRADE-v2.0.md

@@ -16,6 +16,7 @@
   ```
 
   With 2.0:
+
   ```python
   class CommonFields(object):
       name = String()
@@ -23,3 +24,21 @@
   class Pet(CommonFields, Interface):
       pass
   ```
+
+* Meta options as class arguments (**ONLY PYTHON 3**).
+  
+  Before:
+
+  ```python
+  class Dog(ObjectType):
+      class Meta:
+          interfaces = [Pet]
+      name = String()
+  ```
+
+  With 2.0:
+
+  ```python
+  class Dog(ObjectType, interfaces=[Pet]):
+      name = String()
+  ```