Users might not be searching using the search bar: They may want to navigate through the categories links and its subcategories links.

This is how you can create a simple Categories Navigation Section displaying all questions inside them:

<ul id="main_navigation">
{% for categories in roots_categories %}
  <li class="category_item">
    <h2>{{ category.name }}</h2>
    {% if category.questions.size > 0 %}
      <ul class="question_list">
        {% for question in category.question %}
          <li><a href="{{ question.url }}">{{ question.name }}</a>
        {% endfor %}
      </ul>
    {% endif %}
  </li>
{% endfor %}
</ul>