feat: enable site admin to disable WebAppManifest (#2056)

wowchemy/layouts/partials/site_head.html

@@ -174,7 +174,10 @@
   <link rel="alternate" href="{{.RelPermalink}}" type="application/rss+xml" title="{{site.Title}}">
   {{ end }}
 
+  {{ if site.Home.OutputFormats.Get "WebAppManifest" }}
   <link rel="manifest" href="{{ "index.webmanifest" | relLangURL }}">
+  {{ end }}
+
   <link rel="icon" type="image/png" href="{{(partial "functions/get_icon" 32).RelPermalink}}">
   <link rel="apple-touch-icon" type="image/png" href="{{(partial "functions/get_icon" 192).RelPermalink}}">
 

wowchemy/layouts/slides/baseof.html

@@ -12,7 +12,10 @@
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="generator" content="Source Themes Academic {{ site.Data.academic.version }}">
 
+  {{ if site.Home.OutputFormats.Get "WebAppManifest" }}
   <link rel="manifest" href="{{ "index.webmanifest" | relLangURL }}">
+  {{ end }}
+  
   <link rel="icon" type="image/png" href="{{(partial "functions/get_icon" 32).RelPermalink}}">
   <link rel="apple-touch-icon" type="image/png" href="{{(partial "functions/get_icon" 192).RelPermalink}}">