Update favicon, move to separate shortcode for customization

layouts/partials/docs/brand.html

@@ -1,7 +1,7 @@
 <h2 class="book-brand">
   <a class="flex align-center" href="{{ cond (not .Site.Home.File) .Sites.Default.Home.RelPermalink .Site.Home.RelPermalink }}">
     {{- with .Site.Params.BookLogo -}}
-    <img src="{{ . | relURL }}" alt="Logo" />
+    <img src="{{ . | relURL }}" alt="Logo" class="book-icon" />
     {{- end -}}
     <span>{{ .Site.Title }}</span>
   </a>

layouts/partials/docs/html-head-favicon.html

@@ -0,0 +1 @@
+<link rel="icon" href="{{ .Site.Params.BookFavicon | default "favicon.png" | relURL }}" >

layouts/partials/docs/html-head.html

@@ -12,10 +12,10 @@
 {{- template "_internal/opengraph.html" . -}}
 
 <title>{{ partial "docs/html-head-title" . }}</title>
+{{ partial "docs/html-head-favicon" . }}
 
 {{- $manifest := resources.Get "manifest.json" | resources.ExecuteAsTemplate "manifest.json" . }}
 <link rel="manifest" href="{{ $manifest.RelPermalink }}">
-<link rel="icon" href="{{ .Site.Params.BookFavicon | default "favicon.png" | relURL }}" >
 <link rel="canonical" href="{{ .Permalink }}">
 
 {{- range .Translations }}