website: remove dead udhcp link

The udhcp.busybox.net site is gone, it's now pointing to bugzilla.
udhcp has been a part of busybox for some time now.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/header.html

@@ -61,7 +61,6 @@
     <br><a href="http://busybox.net/">BusyBox</a>
     <br><a href="http://uclibc.org/">uClibc.org</a>
     <br><a href="http://cxx.uclibc.org/">uClibc++</a>
-    <br><a href="http://udhcp.busybox.net/">udhcp</a>
     <br><a href="http://www.scratchbox.org/">Scratchbox</a>
     <br><a href="http://openembedded.org/">OpenEmbedded</a>
     <br><a href="http://www.ucdot.org/">uCdot</a>