[docs] codecs.encode/decode documentation inconsistency (issue 21488)

[victor.stinner at gmail.com]

http://bugs.python.org/review/21488/diff/11863/Doc/library/codecs.rst
File Doc/library/codecs.rst (right):

http://bugs.python.org/review/21488/diff/11863/Doc/library/codecs.rst#newcode29
Doc/library/codecs.rst:29: encoding is ``utf-8``.
You should also mention the default error handler:

The default *encoding* is ``'utf-8'`` and the default *error* handler is
``'strict'``.

http://bugs.python.org/review/21488/diff/11863/Doc/library/codecs.rst#newcode40
Doc/library/codecs.rst:40: encoding is ``utf-8``.
The default *encoding* is ``'utf-8'`` and the default *error* handler is
``'strict'``.

http://bugs.python.org/review/21488/