Remove mention of 2.5 testing from docs

Travis CI testing against python 2.5 was removed in 0001199.

Author: bd808

docs/index.rst

@@ -55,7 +55,7 @@ implements the magic method ``__contains__`` which python calls when the
 Python Version Compatibility
 ****************************
 
-`Travis CI`_ automatically runs tests against python 2.5, 2.6, 2.7, 3.2, 3.3 and pypy.
+`Travis CI`_ automatically runs tests against python 2.6, 2.7, 3.2, 3.3 and pypy.
 
 Current test status: |build status|