fix readme blocks

Author: danthedeckie

README.rst

@@ -447,12 +447,14 @@ There is an additional layer of protection you can add in by passing in ``allowe
 makes all attribute access based opt-in rather than opt-out - which is a lot safer design:
 
 .. code-block:: pycon
+
     >>> simpleeval("' hello   '.strip()", allowed_attrs={})
 
 will throw FeatureNotAvailable - as we've now disabled all attribute access.  You can enable some
 reasonably sensible defaults with BASIC_ALLOWED_ATTRS:
 
 .. code-block:: pycon
+
     >>> from simpleeval import simpleeval, BASIC_ALLOWED_ATTRS
     >>> simpleeval("'  hello   '.strip()", allowed_attrs=BASIC_ALLOWED_ATTRS)