[docs] Typo in the Python 2.7 tutorial, section 3.1.2

[Ted Clark]

There's a typo in the Python 2.7 tutorial, section 3.1.2:

>>> 'doesn\'t'  # use \' to escape the single quote...
"doesn't"

should be:

>>> 'doesn\'t'  # use \' to escape the single quote...
'doesn\'t'