updating comment form input to be a button

opentech/apply/activity/templates/activity/include/comment_form.html

@@ -3,6 +3,6 @@
     <form class="form form--comments" method="post" id="comment-form">
         {% csrf_token %}
         {{ comment_form }}
-        <input id="comment-form-submit" name="form-submitted" form="comment-form" class="button button--primary" type="submit" value="Add message">
+        <button id="comment-form-submit" name="form-submitted" form="comment-form" class="button button--primary" type="submit" value="comment">Add message</button>
     </form>
 </div>