Site Health: Add a link to "Debugging in WordPress" support article to fatal PHP error handler's default message.

Props garrett-eclipse, tobifjellner, dkarfa, hareesh-pillai.
Fixes #47681.

git-svn-id: https://develop.svn.wordpress.org/trunk@46151 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-fatal-error-handler.php

@@ -183,6 +183,14 @@ class WP_Fatal_Error_Handler {
 			$message = __( 'There has been a critical error on your website.' );
 		}
 
+		$message = sprintf(
+			'<p>%s</p><p><a href="%s">%s</a></p>',
+			$message,
+			/* translators: Documentation explaining debugging in WordPress. */
+			esc_url( __( 'https://wordpress.org/support/article/debugging-in-wordpress/' ) ),
+			__( 'Learn more about debugging in WordPress.' )
+		);
+
 		$args = array(
 			'response' => 500,
 			'exit'     => false,