[Gimp-docs] "What's New" page should link to the new tools

[Ori Avtalion]

Hi,

As a newcomer to GIMP 2.4, the What's New page is the first thing I
looked for before trying out the new version.

<http://docs.gimp.org/en/gimp-introduction-whats-new.html>

While it does a good job of describing the new tools, I had to manually
look up their respective pages in the TOC to get more information about
them.

I think the page should be filled with links for more information on
each presented tool.

-Ori