minor update

layouts/partials/head.html

@@ -10,7 +10,7 @@
 	<meta name="author" content="{{ . }}">{{ end }}
 	{{ hugo.Generator }}
 
-	{{ $url := .site.BaseURL }}
+	{{ $url := .Site.BaseURL }}
 	{{ template "_internal/opengraph.html" . }}
 	<meta name="og:image" content="{{ with .Params.image }}{{$url}}{{ . }}{{ else }}{{$url}}{{ `images/Cover.jpg` }}{{end}}">
 	{{ template "_internal/twitter_cards.html" . }}