add .Site.BaseURL to nav

layouts/partials/site-navigation.html

@@ -1,6 +1,6 @@
 <nav class="pv3 ph3 ph4-ns" role="navigation">
   <div class="flex-l justify-between items-center center">
-    <a href="/" class="f3 fw2 hover-white no-underline white-90 dib">
+    <a href="{{ .Site.BaseURL }}" class="f3 fw2 hover-white no-underline white-90 dib">
       {{ .Site.Title }}
     </a>
     <div class="flex-l items-center">