Add 'sponsors' anchor to the sponsor section

Author: yasulab

app/views/custom_widget/show.html.erb

@@ -110,7 +110,7 @@
   </section>
 </div>
 
-<div>
+<div id="sponsors">
   <section class='detail-introduction sponsors_logo text-center'>
     <h2>スポンサー</h2>
     <ul>