Fixes typos in tempest/api

Just some typos

Change-Id: I062b60e6b20bb116547f613556cf976d58f81d40
diff --git a/tempest/api/identity/admin/v3/test_roles.py b/tempest/api/identity/admin/v3/test_roles.py
index 980323a..a238c46 100644
--- a/tempest/api/identity/admin/v3/test_roles.py
+++ b/tempest/api/identity/admin/v3/test_roles.py
@@ -54,7 +54,7 @@
         resp[1], _ = cls.v3_client.delete_group(cls.group_body['id'])
         resp[2], _ = cls.v3_client.delete_user(cls.user_body['id'])
         resp[3], _ = cls.v3_client.delete_project(cls.project['id'])
-        # NOTE(harika-vakadi): It is necessary to disable the domian
+        # NOTE(harika-vakadi): It is necessary to disable the domain
         # before deleting,or else it would result in unauthorized error
         cls.v3_client.update_domain(cls.domain['id'], enabled=False)
         resp[4], _ = cls.v3_client.delete_domain(cls.domain['id'])