Toolbar: Link to Learn WordPress in the WordPress Logo menu.

This aims to make the various resources on learn.wordpress.org more easily available.

Props jeherve, mikinc860, audrasjb, sabernhardt, courane01, devmuhib, dhrumilk, estelaris, hellofromTonya.
Fixes #58820.

git-svn-id: https://develop.svn.wordpress.org/trunk@56720 602fd350-edb4-49c9-b593-d223f7449a82

Author: costdev

src/wp-includes/admin-bar.php

@@ -194,6 +194,16 @@ function wp_admin_bar_wp_menu( $wp_admin_bar ) {
 		)
 	);
 
+	// Add learn link.
+	$wp_admin_bar->add_node(
+		array(
+			'parent' => 'wp-logo-external',
+			'id'     => 'learn',
+			'title'  => __( 'Learn WordPress' ),
+			'href'   => 'https://learn.wordpress.org/',
+		)
+	);
+
 	// Add forums link.
 	$wp_admin_bar->add_node(
 		array(