Docs: Avoid using “CPT” instead of “custom post type”.

Additionally, when referring to built in Core post types, “custom” is unnecessary.

This also adds a period to the end of the `wp_global_styles` post type description.

Follow up to [38829], [51003], [52041], [52049], [52062].

See #53399, #54335, #54336.

git-svn-id: https://develop.svn.wordpress.org/trunk@52110 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/post.php

@@ -450,7 +450,7 @@ function create_initial_post_types() {
 		'wp_global_styles',
 		array(
 			'label'        => __( 'Global Styles' ),
-			'description'  => __( 'CPT to store user design tokens' ),
+			'description'  => __( 'Post type for storing user design tokens.' ),
 			'public'       => false,
 			'_builtin'     => true, /* internal use only. don't use this when registering your own post type. */
 			'show_ui'      => false,