Updates README for the correct URL to the docs

Author: msaito8623

README.rst

@@ -19,7 +19,7 @@ Installation
 Documentation
 =============
 
-*discriminative_lexicon_model* uses ``sphinx`` to create a documentation manual. The documentation is hosted on `Read the Docs <http://discriminative_lexicon_model.readthedocs.io/en/latest/>`_.
+*discriminative_lexicon_model* uses ``sphinx`` to create a documentation manual. The documentation is hosted on `Read the Docs <http://discriminative-lexicon-model.readthedocs.io/en/latest/>`_.
 
 
 Authors and Contributers