updated wagtail font with unified user icon and site icon

wagtail/contrib/wagtailstyleguide/templates/wagtailstyleguide/base.html

@@ -416,6 +416,7 @@
                 <li class="icon icon-date">date</li>
                 <li class="icon icon-time">time</li>
                 <li class="icon icon-form">form</li>
+                <li class="icon icon-site">site</li>
             </ul>
 
         </section>

wagtail/wagtailadmin/static/wagtailadmin/scss/components/icons.scss

@@ -250,6 +250,9 @@
 .icon-form:before{
     content:"$";
 }
+.icon-site:before{
+    content:"@";
+}
 
 .icon.text-replace{
     font-size:0em;