Merge pull request #189 from smsaladi/patch-1

fix typo

Author: MarkDaoust

site/en/guide/performance/overview.md

@@ -114,7 +114,7 @@ equal to the number of physical cores rather than logical cores.
 config = tf.ConfigProto()
 config.intra_op_parallelism_threads = 44
 config.inter_op_parallelism_threads = 44
-tf.session(config=config)
+tf.Session(config=config)
 ```
 
 The [comparing compiler optimizations](#comparing-compiler-optimizations)