Fix typo in README

From: Fabian Pedregosa <fabian.pedregosa@inria.fr>

git-svn-id: https://scikit-learn.svn.sourceforge.net/svnroot/scikit-learn/trunk@415 22fbfee3-77ab-4535-9bad-27d1bd3bc7d8

README

@@ -3,7 +3,7 @@
 About
 =====
 
-scikit.learn is a python module for machine learning built on top of
+scikits.learn is a python module for machine learning built on top of
 scipy.
 
 The project was started in 2007 by David Cournapeu as a Google Summer