docs(actionSheet): improve docs

scripts/docs/tag-defs/tag-defs.js

@@ -1,4 +1,5 @@
 module.exports = [
+  {'name': 'advanced'},
   {'name': 'demo'},
   {'name': 'usage'}
 ];

scripts/docs/templates/common.template.html

@@ -276,6 +276,13 @@ docType: "<$ doc.docType $>"
 
 <@- endif -@>
 
+<@ block advanced @>
+<@- if doc.advanced -@>
+<h2><a class="anchor" name="advanced" href="#advanced"></a>Advanced</h2>
+<$ doc.advanced | marked $>
+<@- endif -@>
+<@ endblock @>
+
 <!-- related link -->
 <@- if doc.see @>