Add a documentation page

templates/navbar.html

@@ -0,0 +1,35 @@
+{% set tabs = [
+  ("map", "Home"),
+  ("documentation", "Documentation"),
+] %}
+
+{% macro navbar() %}
+<nav id="nav" class="navbar navbar-expand navbar-light bg-light">
+  <div class="container-fluid">
+    <a class="navbar-brand" href="/map">osm.wikidata.link</a>
+    <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+      {% for page, label in tabs%}
+      <li class="nav-item">
+        <a
+          class="nav-link{% if page == active_tab %} active{% endif %}"
+          href="/{{ page }}">{{ label }}</a>
+      </li>
+      {% endfor %}
+    </ul>
+    <ul class="navbar-nav">
+      {% if username %}
+        <li class="nav-item">
+          <a class="nav-link" href="#">{{ username }}</a>
+        </li>
+        <li class="nav-item">
+          <a class="nav-link" href="/logout">Logout</a>
+        </li>
+      {% else %}
+      <li v-else class="nav-item">
+        <a class="nav-link" href="/login">Login with OpenStreetMap</a>
+      </li>
+      {% endif %}
+    </ul>
+  </div>
+</nav>
+{% endmacro %}