layouts/_default/baseof.html: Enumerate non-post pages in header nav menu

Still need to figure out how to determine which page we're on so we
can set the "active" class accordingly (for Home we have the IsHome
variable the we can check).

layouts/_default/baseof.html

@@ -29,6 +29,9 @@
     <div class="container">
       <nav class="nav blog-nav">
         <a class="nav-link {{ if .IsHome }}active{{ end }}" href="{{ .Site.BaseURL }}">Home</a>
+        {{ range where .Site.Pages "Type" "!=" "post" }}
+        <a class="nav-link" href="{{ .Permalink }}">{{ .Title }}</a>
+        {{ end }}
       </nav>
     </div>
   </div>