Docs: add mention of collections.Counter, collections.OrderedDict backports for Py2.6

Author: edschofield

docs/quickstart.rst

@@ -97,6 +97,7 @@ be accessed under their Python 3 names and locations in Python 2::
         import queue
         import configparser
         from collections import UserList
+        from collections import Counter, OrderedDict   # even on Py2.6
         from itertools import filterfalse, zip_longest
 
         import html

docs/standard_library_imports.rst

@@ -70,7 +70,7 @@ install_hooks() call
 --------------------
 
 The fourth interface to the reorganized standard library is via an
-explicit call to ``install_hooks``::
+explicit call to ``install_hooks()``::
 
     from future import standard_library
     standard_library.install_hooks()
@@ -117,12 +117,13 @@ modules on Py2::
 List of standard library modules
 --------------------------------
 
-The modules available via ``future.moves`` are::
+The modules available from ``future.moves`` via one of the interfaces above are::
 
     import socketserver
     import queue
     import configparser
     from collections import UserList
+    from collections import Counter, OrderedDict   # backported to Py2.6
     from itertools import filterfalse, zip_longest
     
     import html