DOC add get_dummies to reshaping.rst
examples shamelessly from Wes' book

closes #4444

@jreback Did I do something wrong here? This doesn't appear at bottom of web page: http://pandas.pydata.org/pandas-docs/dev/reshaping.html#tiling
 nope

doc build stuck somehow (as of oct 11)

@wesm ping!
 docs are updated! http://pandas.pydata.org/pandas-docs/dev/reshaping.html
(there was a typo here which I just fixed...fyi)
