Add Google Adsense Code Snippet

Author: chrisspiegl

_includes/layout.pug

@@ -163,3 +163,5 @@ body
     })
     Array.prototype.forEach.call(document.querySelectorAll('.footnotes.footnote-print-only, .footnotes .footnote-print-only'), e => e.classList.remove('footnote-print-only'))
     Array.prototype.forEach.call(document.querySelectorAll('.footnote-backref'), (el) => { el.href = el.href.replace('#', '#lf-') })
+  //- Google Adsense
+  script(async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-3261283140705533" crossorigin="anonymous")