覚え書き。
<li class="nav-divider"></li>
参考サイト
twitter bootstrap – How can I get “divider” displayed for “nav-pills” and “nav-stacked” – Stack Overflow
http://stackoverflow.com/questions/20664117/how-can-i-get-divider-displayed-for-nav-pills-and-nav-stacked
Using dropdowns / Navs / Bootstrap
http://getbootstrap.com/components/#nav-dropdowns