Add aliased_fields example in README.md

Author: Nabellaleen

README.md

@@ -47,6 +47,8 @@ class User(SQLAlchemyObjectType):
         only_fields = ("name",)
         # exclude specified fields
         exclude_fields = ("last_name",)
+        # alias specified fields
+        aliased_fields = {'name': 'first_name'}
 
 class Query(graphene.ObjectType):
     users = graphene.List(User)