ar-collapse" id="navbarSupportedContent">
              <ul id="page-nav" class="nav flex-column nav-vertical-2">
                <li class="nav-item">
                  <a class="nav-link" data-toggle="collapse" href="#menu-2" role="button" aria-expanded="true" aria-controls="menu-2">Installation</a>
                  <div class="collapse" id="menu-2" data-parent="#page-nav">
                    <div>
                      <ul class="nav flex-column">
                        <li class="nav-item">
         