fix(partials/head): Allow zooming

Disabling zooming is problematic for people with low vision (https://dequeuniversity.com/rules/axe/3.0/meta-viewport).

layouts/partials/head.html

   {{ .Hugo.Generator }}
 
   <!-- Enable responsiveness on mobile devices-->
-  <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
 
   {{ if .IsHome -}}
   <title>{{ .Site.Title }}</title>