Document class .in is required in addition to .fade for tabs

[kddawson]

Took me a while to figure what was happening, but to get .fade .to work with a .tab-pane, you also need to add the .in class to the first tab. An update to this effect at http://getbootstrap.com/javascript/#tabs would be most useful.

[Joyrex]

Bootstrap 2.x had this as well