Add subsections to the navigation bar (e.g. publications, projects)

[Rezenders]

So, I was checking how to do this and we can modify the masthead.html to something similar to the nav_list like this:

        <li class="masthead__menu-item masthead__menu-item--lg"><a href="{{ base_path }}/">{{ site.title }}</a></li>
        {% for link in site.data.navigation.main %}
          {% if link.url contains 'http' %}
            {% assign domain = '' %}
          {% else %}
            {% assign domain = base_path %}
          {% endif %}
          <li class="masthead__menu-item"><a href="{{ domain }}{{ link.url }}">{{ link.title }}</a>
            {% if link.children != null %}
            <ul>
              {% for child in link.children %}
                {% if child.url contains 'http' %}
                  {% assign domain = '' %}
                {% else %}
                  {% assign domain = base_path %}
                {% endif %}

                {% comment %}set "active" class on current page{% endcomment %}
                {% if child.url == page.url %}
                  {% assign active = "active" %}
                {% else %}
                  {% assign active = "" %}
                {% endif %}

                <li><a href="{{ domain }}{{ child.url }}" class="masthead__menu-item">{{ child.title }}</a></li>
              {% endfor %}
            </ul>
            {% endif %}
          </li>
        {% endfor %}
      </ul>

And just add entries to the navigation.yml like this:

# main links links
main:
  - title: "Parent Link 1"
    url: /parent-1-page-url/
    children:
      - title: "Child Link 1"
        url: /child-1-page-url/
      - title: "Child Link 2"
        url: /child-2-page-url/

  - title: "Research"
    url: /research/
    children: "Education"

  - title: "Education"
    url: /education/

  - title: "Software"
    url: /software/

  - title: "Team"
    url: /team/

  - title: "Join us"
    url: /join-us/

The only problem is adjusting the html/css to make it look good, for now it looks like this:

[Rezenders]

This is in the nav_sub branch

[chcorbato]

Sounds like we cannot have it with a good enough look. I suggest we do not implement it for the moment. I label it as an enhancement and remove it form the requirements frmo the MVP