Docs: Clarify the file header subpackage for wp-includes/class-walker-page-dropdown.php, introduced in [34109].

Also clarifies the class DocBlock summary and tags for `Walker_PageDropdown`.

See #33413. See #33701.


git-svn-id: https://develop.svn.wordpress.org/trunk@34415 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-walker-page-dropdown.php

@@ -3,15 +3,16 @@
  * Post API: Walker_PageDropdown class
  *
  * @package WordPress
- * @subpackage Template
+ * @subpackage Post
  * @since 4.4.0
  */
 
 /**
- * Create HTML dropdown list of pages.
+ * Core class used to create an HTML drop-down list of pages.
  *
  * @since 2.1.0
- * @uses Walker
+ *
+ * @see Walker
  */
 class Walker_PageDropdown extends Walker {
 	/**