Fixed namespaces example in README
Fixed namespaces example in README

Fixes #66.

solvebio/xmltodict,martinblech/xmltodict,ahlusar1989/xmltodict,CyberTailor/iBlock,pombredanne/xmltodict,butson/xmltodict,CyberTailor/iBlock,haiyangd/xmltodict,pombredanne/xmltodict,bzamecnik/xmltodict,martinblech/xmltodict,lucius-feng/xmltodict,sporgj/xmltodict