Fix simple typos

This commit fixes simple typos.

Change-Id: Ia90452f113e9e8a38b0bb27cd106b84afc8a78d1
diff --git a/neutron/tests/tempest/api/test_qos.py b/neutron/tests/tempest/api/test_qos.py
index 2d688df..4040c0b 100644
--- a/neutron/tests/tempest/api/test_qos.py
+++ b/neutron/tests/tempest/api/test_qos.py
@@ -124,7 +124,7 @@
         # In theory, we could make the test conditional on which ml2 drivers
         # are enabled in gate (or more specifically, on which supported qos
         # rules are claimed by core plugin), but that option doesn't seem to be
-        # available thru tempest.lib framework
+        # available through tempest.lib framework
         expected_rule_types = []
         expected_rule_details = ['type']