Adjust .File usage to get rid of WARNINGs

Note that this requires this fix in Hugo 0.55.2:

https://github.com/gohugoio/hugo/issues/5865

.gitignore

@@ -0,0 +1,2 @@
+public/
+exampleSite/public/

layouts/partials/docs/git-footer.html

@@ -10,9 +10,9 @@
   {{ end }}
   {{ with .Site.Params.BookEditPath }}
   <div>
-    <a href="{{ $.Site.Params.BookRepo }}/{{ . }}/{{ $.File.Path }}" target="_blank" rel="noopener">
+    {{ if $.File }}<a href="{{ $.Site.Params.BookRepo }}/{{ . }}/{{ $.File.Path }}" target="_blank" rel="noopener">
       <img src="{{ "svg/code-fork.svg" | relURL }}" /> Edit this page
-    </a>
+    </a>{{ end }}
   </div>
   {{ end }}
 </div>

layouts/partials/docs/shared.html

@@ -1,10 +1,10 @@
 {{/*These templates contains some more complex logic and shared between partials*/}}
 {{- define "title" -}}
-  {{- if .Pages -}}
-    {{ $sections := split (trim .Dir "/") "/" }}
+  {{- if and .File .Pages -}}
+    {{ $sections := split (trim .File.Dir "/") "/" }}
     {{ $title := index ($sections | last 1) 0 | humanize | title }}
     {{- default $title .Title -}}
-  {{- else -}}
+  {{- else if .File -}}
     {{ $title :=  .File | humanize | title }}
     {{- default $title .Title -}}
   {{- end -}}