Merge pull request #6646 from edx/missed-an-ellipses

Missed an ellipsis

lms/templates/discussion/_underscore_templates.html

@@ -81,7 +81,7 @@
                 <ul class="discussion-errors"></ul>
                 <label class="sr" for="add-new-comment">${_("Add a comment")}</label>
                 <div class="comment-body" id="add-new-comment" data-id="${'<%- wmdId %>'}"
-                data-placeholder="${_('Add a comment...') | h}"></div>
+                data-placeholder="${_('Add a comment') | h}"></div>
                 <div class="comment-post-control">
                     <a class="discussion-submit-comment control-button" href="#">${_("Submit")}</a>
                 </div>