feat(ui): add footer with links to docs and discussions

app/assets/stylesheets/application/components/_site_content.scss

@@ -12,3 +12,10 @@
   overflow-y:scroll;
   overflow-x:hidden;
 }
+
+.siteContent__footer {
+  border-top:1px solid #efefef;
+  margin-top:20px;
+  padding:25px;
+  display:flex;
+}