Fix description for name field

Fix description for name field of edit alarm definition.
(Cherry-picked from 0373c98)

Change-Id: Ibab742e42c11ab63e377cd895b4c73cd1445093a
Task:  6298
Story: 2001507

Author: haruki-yamanashi

monitoring/alarmdefs/templates/alarmdefs/_edit.html

@@ -9,9 +9,9 @@
 
 {% block modal-body %}
     <h3>{% trans "Description" %}:</h3>
-    <p>{% blocktrans %}
-      The Name field is used to identify the notification method.
-    {% endblocktrans %}</p>
+        <p>{% blocktrans %}
+          The Name field is used to identify the alarm definition.
+        {% endblocktrans %}</p>
     <p>{% blocktrans %}
       The Expression field  which if true, triggers a notification to be sent.
       See <a href="https://github.com/openstack/monasca-api/blob/master/docs/monasca-api-spec.md#alarm-definition-expressions" target="_blank">Alarm Expressions</a> for how to write an expression.