<nav> element have to have a
<ul> in it?
On this page http://html5doctor.com/nav-element/, it mentions how to use the
<nav> tag for semantic reasons.
In every example, it uses the
<ul> tag, and mentions using it.
Is this required by the HTML 5 specification or is it just recommended by the author?
No , it doesn’t.
A nav element doesn’t have to contain a list, it can contain other kinds of content as well. In this navigation block, links are provided in prose:
HTML shortened for simplicity and brevity.