added adsense validation

docs/_layouts/main.html

@@ -3,6 +3,7 @@
 	<meta charset="utf-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1">
 	<meta name="theme-color" content="#ffffff">
+	<meta name="google-adsense-account" content="ca-pub-3775454102488616">
 	<title>{{ page.title }}</title>
 	{% include link_favicon.html %}
 	{% include link_amp.html %}