Docs: Bring the file header and class DocBlock summaries for class-wp-widget.php in-line with the intention of the docs standard:

* File headers: _What_ the file is
* Class DocBlocks: What purpose the class serves. Mentioning the class name in the class DocBlock is redundant

See #33413


git-svn-id: https://develop.svn.wordpress.org/trunk@33816 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-widget.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Class file for WP_Widget
+ * WP_Widget class, base class for creating widgets
  *
  * @package WordPress
  * @subpackage Widgets
@@ -8,7 +8,7 @@
  */
 
 /**
- * WP_Widget class.
+ * Class extended to register widgets for the core Widgets API.
  *
  * This class must be extended for each widget and WP_Widget::widget(), WP_Widget::update()
  * and WP_Widget::form() need to be overridden.