add markdown toc stuff

docs/components/navs.md

@@ -5,6 +5,11 @@ title: Navs
 
 Navigation available in Bootstrap share general markup and styles, from the base `.nav` class to the active and disabled states. Swap modifier classes to switch between each style.
 
+## Contents
+
+* Will be replaced with the ToC, excluding the "Contents" header
+{:toc}
+
 ## Regarding accessibility
 
 If you are using navs to provide a navigation bar, be sure to add a `role="navigation"` to the most logical parent container of the `<ul>`, or wrap a `<nav>` element around the whole navigation. Do not add the role to the `<ul>` itself, as this would prevent it from being announced as an actual list by assistive technologies.