Fix flake8 H404 errors

Fix H404 error and start enforcing it.

Trivialfix

Change-Id: I0c062733660031faf43838798a697daf6674ef14
diff --git a/neutron_tempest_plugin/api/test_subnetpools.py b/neutron_tempest_plugin/api/test_subnetpools.py
index 25d9780..9d927cf 100644
--- a/neutron_tempest_plugin/api/test_subnetpools.py
+++ b/neutron_tempest_plugin/api/test_subnetpools.py
@@ -58,7 +58,8 @@
     new_prefix = u'10.11.15.0/24'
     larger_prefix = u'10.11.0.0/16'
 
-    """
+    """Test Subnet Pools
+
     Tests the following operations in the Neutron API using the REST client for
     Neutron:
 
@@ -327,9 +328,7 @@
     @decorators.idempotent_id('4c6963c2-f54c-4347-b288-75d18421c4c4')
     @utils.requires_ext(extension='default-subnetpools', service='network')
     def test_tenant_create_non_default_subnetpool(self):
-        """
-        Test creates a subnetpool, the "is_default" attribute is False.
-        """
+        """Test creates a subnetpool, the "is_default" attribute is False."""
         created_subnetpool = self._create_subnetpool()
         self.assertFalse(created_subnetpool['is_default'])