Fixed typo

public/app/features/alerting/partials/notification_edit.html

@@ -71,7 +71,7 @@
         <textarea rows="7" class="gf-form-input width-25" required ng-model="ctrl.model.settings.addresses"></textarea>
       </div>
       <div class="gf-form">
-        <span>You can center multiple email address using a ";" seperator</span>
+        <span>You can enter multiple email addresses using a ";" separator</span>
       </div>
     </div>