doc: Fix some issues with blocks.

Author: QuLogic

docs/conversion_limitations.rst

@@ -20,7 +20,7 @@ Contributions to the ``lib2to3``-based fixers for ``futurize`` and
 Known limitations
 -----------------
 
-``futurize`` doesn't currently make this change automatically::
+``futurize`` doesn't currently make this change automatically:
 
 1. Strings containing ``\U`` produce a ``SyntaxError`` on Python 3. An example is::
 

docs/str_object.rst

@@ -80,8 +80,8 @@ same behaviours as Python 3's :class:`str`::
     >>> assert s.split('B') == ['A', 'CD']
 
 .. If you must ensure identical use of (unicode) strings across Py3 and Py2 in a
-.. single-source codebase, you can wrap string literals in a :func:`~str` call, as
-..  follows::
+.. single-source codebase, you can wrap string literals in a :func:`~str` call,
+.. as follows::
 ..     
 ..     from __future__ import unicode_literals
 ..     from future.builtins import *