Add Customizer docs.

Props ericlewis.
See #33503.


git-svn-id: https://develop.svn.wordpress.org/trunk@33911 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-setting.php

@@ -24,6 +24,8 @@ class WP_Customize_Setting {
 	public $manager;
 
 	/**
+	 * Unique string identifier for the setting.
+	 *
 	 * @access public
 	 * @var string
 	 */
@@ -74,6 +76,9 @@ class WP_Customize_Setting {
 	 */
 	public $dirty = false;
 
+	/**
+	 * @var array
+	 */
 	protected $id_data = array();
 
 	/**
@@ -148,7 +153,8 @@ class WP_Customize_Setting {
 	protected $_original_value;
 
 	/**
-	 * Handle previewing the setting.
+	 * Set up filters for the setting so that the preview request
+	 * will render the drafted changes.
 	 *
 	 * @since 3.4.0
 	 */