H99: broken link in Description

[momdo]

EPUB 3 defines the page list in its navigation document

• https://www.w3.org/publishing/epub3/epub-packages.html#sec-nav-pagelist is 404 not found
• its replacement https://www.w3.org/publishing/epub32/epub-packages.html#sec-nav-pagelist is marked as outdated

[patrickhlauke]

possibly even better: https://www.w3.org/TR/epub/#sec-nav-pagelist ?