Start work on search feature with lunr

layouts/partials/docs/menu.html

@@ -1,5 +1,6 @@
 <nav>
 {{ partial "docs/brand" . }}
+{{ partial "docs/search" . }}
 {{ partial "docs/inject/menu-before" . }}
 
 {{ if .Site.Params.BookMenuBundle }}
@@ -11,6 +12,13 @@
 {{ partial "docs/inject/menu-after" . }}
 </nav>
 
-{{ if .Site.Params.BookEnableJS }}
-  {{ template "jsmenu" . }}
-{{ end }}
+<!-- Restore menu position as soon as possible to avoid flickering -->
+<script>
+(function() {
+  var menu = document.querySelector("aside.book-menu nav");
+  addEventListener("beforeunload", function(event) {
+    localStorage.setItem("menu.scrollTop", menu.scrollTop);
+  });
+  menu.scrollTop = localStorage.getItem("menu.scrollTop");
+})();
+</script>