config_service: release the UI to the front page

appengine/config_service/ui/src/config-ui/config-ui.html

 <!--
   Copyright 2017 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 -->
 
 <link rel="import" href="../../bower_components/polymer/polymer.html">
 <link rel="import" href="../../bower_components/paper-search/paper-search-bar.html">
 <link rel="import" href="../../bower_components/app-route/app-location.html">
 <link rel="import" href="../../bower_components/app-route/app-route.html">
@@ skipping 20 matching lines @@
       .logo { 
         height: 50px;
       }
 
       .right { margin-left:15px; }
 
       .title {
         font-size: 125%;
         color: white;
       }
+
+      .link {
+        font-size: 75%;
+        color: white;
+        margin-right: 10px;
+      }
     </style>
 
     <app-drawer-layout fullbleed force-narrow>
       <app-header-layout>
         <app-header reveals slot="header">
           <app-toolbar>
             <!--<image class="logo" src="/static/images/chromium.png"/>-->
             <div class="title" main-title>
               Configuration Service
             </div>
 
+            <a href="https://luci-config.appspot.com/_ah/api/explorer" 
+               class="link" 
+               target="_blank"> APIs explorer 
+            </a>
+
             <template is="dom-if" if="[[client_id]]">
               <auth-signin
                   class="right"
                   client_id="[[client_id]]"
                   auth_headers="{{auth_headers}}"
                   profile="{{profile}}"
                   signed_in="{{signed_in}}">
               </auth-signin>
             </template>
             <template is="dom-if" if="[[!client_id]]">
@@ skipping 58 matching lines @@
           // If the path is blank, redirect to /
           if (!this.route.path) {
             this.set('route.path', '/');
           }
         });
       },
 
     });
   </script>
 </dom-module>