Update README

Author: quiqueporta

README.rst

@@ -142,24 +142,6 @@ Invariants
     #<__main__.Point at 0x7f2bd043c780>
 
 
-Mutable types not allowed
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. code-block:: python
-
-    from simple_value_object import ValueObject, invariant
-
-    class AValueObject(ValueObject):
-
-        def __init__(self, an_arg):
-            pass
-
-    AValueObject(an_arg={'key': 'value'})
-    #MutableTypeNotAllowedException: 'an_arg' cannot be a mutable data type.
-
-    AValueObject({'key': 'value'})
-    #MutableTypeNotAllowedException: Mutable args are not allowed.
-
 ValueObject within ValueObject
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~