Docs: Add missing documentation for the first parameter of the `big_image_size_threshold` filter.

Props dkarfa, desrosj, earnjam.
Fixes #48214.
Built from https://develop.svn.wordpress.org/trunk@46398


git-svn-id: http://core.svn.wordpress.org/trunk@46197 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/image.php

@@ -235,6 +235,7 @@ function wp_create_image_subsizes( $file, $attachment_id ) {
 	 *
 	 * @since 5.3.0
 	 *
+	 * @param int    $threshold     The threshold value in pixels. Default 2560.
 	 * @param array  $imagesize     Indexed array of the image width and height (in that order).
 	 * @param string $file          Full path to the uploaded image file.
 	 * @param int    $attachment_id Attachment post ID.

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-beta2-46397';
+$wp_version = '5.3-beta2-46398';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.