change how navs are fetched

    there's just main: and nav: in _data/navigations.yml
    each branch has its own navigations

_includes/nav_list

-{% assign navigation = site.data.navigation.navs | where: "name", include.nav | map: "nav" | first %}
+{% assign navigation = site.data.navigation.nav %}
 
 <nav class="nav__list">
   {% if page.sidebar.title %}<h3 class="nav__title" style="padding-left: 0;">{{ page.sidebar.title }}</h3>{% endif %}