gui: Make 'Nearby devices' look like links (fixes #6057) (#6165)

- The 'help-box' with nearby devices will appear only when there are
  any nearby devices
- IDs of nearby devices will look like links (i.e. underlined when
  hovered over)

gui/default/syncthing/device/editDeviceModalView.html

@@ -15,10 +15,10 @@
               <datalist id="discovery-list">
                 <option ng-repeat="id in discovery" value="{{id}}" />
               </datalist>
-              <p class="help-block" ng-if="discovery">
+              <p class="help-block" ng-if="discovery && discovery.length !== 0">
                 <span translate>You can also select one of these nearby devices:</span>
                 <ul>
-                  <li ng-repeat="id in discovery"><a ng-click="currentDevice.deviceID = id">{{id}}</a></li>
+                  <li ng-repeat="id in discovery"><a href="#" ng-click="currentDevice.deviceID = id">{{id}}</a></li>
                 </ul>
               </p>
               <p class="help-block">