ADD: warning for subscription name

ADD: subscription name warning

Author: ned29

src/main/resources/templates/subscription.html

@@ -96,6 +96,7 @@ <h3 class="modal-title text-center" id="formHeader">Subscription Form</h3>
                             <div class="form-group">
                                 <label class="pl-1 control-label font-weight-bold">SubscriptionName</label>
                                 <div>
+                                  <font color="red" size="2">Only numbers,letters and underscore allowed</font>
                                     <input id="subscriptionNameInput" data-toggle="tooltip" title="Specify a SubsciptionName" data-bind="textInput:$data.subscriptionName"
                                         name="subscriptionName" placeholder="subscriptionName" class="form-control display-inline-table" type="text"
                                     />