added note to nav element about use of list markup

Hi all,

after recent discussion on list [1] I added a note [2] in the 5.1 spec [3]
to clarify nav element usage


Please review at your leisure, feedback welcome and appreciated.


[1] http://lists.w3.org/Archives/Public/public-html/2013Feb/0052.html
[2]
https://github.com/w3c/html/commit/4105037c575e6068e644f987375cf90819fb1a9e
[3]
http://www.w3.org/html/wg/drafts/html/master/sections.html#the-nav-element

-- 
with regards

Steve Faulkner

<http://www.paciellogroup.com/resources/wat-ie-about.html>