Set missing link

lib/views/admin/notification.html

@@ -147,7 +147,7 @@
       </p>
       <h4>1. Register Slack App</h4>
       <p>
-      Create App from this link, and fill the form out as below:
+      Create App from <a href="https://api.slack.com/applications/new">this link</a>, and fill the form out as below:
       </p>
       <dl class="dl-horizontal">
         <dt>App Name</dt> <dd><code>Crowi</code> </dd>