plugins/advanced-plugin-concepts: clarify best-practice

Fixes jquerygh-513
Closes  jquerygh-526

Author: AurelioDeRosa

page/plugins/advanced-plugin-concepts.md

@@ -240,10 +240,14 @@ A bad implementation:
 
 ```
 // Plugin code
-$( "<div id=\"the-gallery-wrapper\" />").appendTo( "body" );
+$( "<div class='gallery-wrapper' />" ).appendTo( "body" );
 
-$( "#the-gallery-wrapper" ).append( "..." );
+$( ".gallery-wrapper" ).append( "..." );
+```
+
+To allow users to access and even manipulate those information, you can store them in a variable containing the settings of your plugin. A better implementation of the previous code is shown below:
 
+```
 // Retain an internal reference:
 var wrapper = $( "<div />" )
 	.attr( settings.wrapperAttrs )
@@ -258,7 +262,7 @@ Notice that we've created a reference to the injected wrapper and we're also cal
 ```
 var defaults = {
 	wrapperAttrs : {
-		id: "gallery-wrapper"
+		class: "gallery-wrapper"
 	},
 	// ... rest of settings ...
 };