Docs: Clarify that the second parameter passed to a shortcode callback is the shortcode content or null, rather than the content the shortcode was found in.

See #37222.

Built from https://develop.svn.wordpress.org/trunk@41283


git-svn-id: http://core.svn.wordpress.org/trunk@41123 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/shortcodes.php

@@ -56,9 +56,9 @@ $shortcode_tags = array();
  * @param string   $tag      Shortcode tag to be searched in post content.
  * @param callable $callback The callback function to run when the shortcode is found.
  *                           Every shortcode callback is passed three parameters by default,
- *                           including an array of attributes (`$atts`), the content
- *                           the shortcode was found in (`$content`), and finally
- *                           the shortcode tag itself (`$shortcode_tag`), in that order.
+ *                           including an array of attributes (`$atts`), the shortcode content
+ *                           or null if not set (`$content`), and finally the shortcode tag
+ *                           itself (`$shortcode_tag`), in that order.
  */
 function add_shortcode( $tag, $callback ) {
 	global $shortcode_tags;

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41282';
+$wp_version = '4.9-alpha-41283';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.