Added GraphLassoCV changes to whatsnew.rst
[DOC] Corrected errors in clustering documentation

Some informations given in the narrative documentation about K-means
were wrong (stopping criteria, mainly).

Fixed some typos and spelling errors as well.
[DOC] fixed a typo in an warning message.
One more typo fixed
Merge pull request #2247 from pgervais/docfixes

Doc fixes
ENH consistency mse=> mean_squared_error ari => adjusted_rand_score
FIX docstring