graph(create annotation): use single description for range

public/app/features/dashboard/partials/addAnnotationModal.html

@@ -42,8 +42,7 @@
           </div>
 
           <div>
-            <h6 ng-if="!ctrl.annotationTimeTo">Description</h6>
-            <h6 ng-if="ctrl.annotationTimeTo">Description Start</h6>
+            <h6>Description</h6>
           </div>
           <div class="gf-form-group share-modal-options">
             <div class="gf-form">
@@ -51,18 +50,6 @@
             </div>
           </div>
 
-
-          <div ng-if="ctrl.annotationTimeTo">
-            <div>
-              <h6>Description Stop</h6>
-            </div>
-            <div class="gf-form-group share-modal-options">
-              <div class="gf-form">
-                <textarea rows="3" class="gf-form-input width-27" ng-model="ctrl.annotationTextTo"></textarea>
-              </div>
-            </div>
-          </div>
-
           <div class="gf-form-button-row">
             <button class="btn gf-form-btn width-10 btn-success" ng-click="ctrl.addAnnotation()">
               <i class="fa fa-pencil"></i>