Update tempest test sample in devstack/README.md

As part of bp:tempest-repo-restructure, the scenario directory is added and
scenario tests are moved there. The tempest test sample should be updated
in README.md.

Fixes bug #1207109

Change-Id: I25067e4b42697985e8f4b808fad5eb801c805f9f
diff --git a/README.md b/README.md
index 3a47fc3..8bca977 100644
--- a/README.md
+++ b/README.md
@@ -179,7 +179,7 @@
 If tempest has been successfully configured, a basic set of smoke tests can be run as follows:
 
     $ cd /opt/stack/tempest
-    $ nosetests tempest/tests/network/test_network_basic_ops.py
+    $ nosetests tempest/scenario/test_network_basic_ops.py
 
 # Multi-Node Setup