v4: .dropdown-header has margin-bottom

Created by: bellwood

Bootstrap 2.3.2 and 3 nav headers (and now dropdown-header) kept tight to the items listed below them:

http://getbootstrap.com/2.3.2/components.html#nav-lists

http://getbootstrap.com/components/#dropdowns-headers

...just 3px of padding top and bottom, no margin

v4 however keeps the 8px or .5 Rem margin added by the H6 plus the 3px of padding top and bottom and as a result its distanced away from the sub-items:

http://v4-alpha.getbootstrap.com/components/dropdowns/#menu-headers

If this purely a function of using H6 for the header (ergo, I should be using another element) or an item that needs to be addressed in the styles?

Thank you =)