misleading dates on developer portal

[eml <enric meinhardt upf edu>]

The page at

http://developer.gnome.org/

has links to current documentation.  However, the only visible date on
this site is from 2006.  This is misleading, as it may suggest that the
rest of the documentation is obsolete.

Maybe there should be dates for each of the entries in this page,
displaying the last update of each section.

Otherwise, the site is really useful for gtk and gnome developers.
Thanks,
enric.