I can't produce this summary — the "article text" supplied is just the website's navigation menu and header (menu items like "Music," "Film," "Shop," "Mailing List," and an unrelated "Cover Story | Yard Act" link), not the actual article content about Angus Young and Slash. No details about the song, the riff, or their quotes were included.

Could you paste the actual body text of the article, or confirm if you'd like me to try fetching the URL directly?