Add note to changelog saying it's no longer updated.

also, add pointer to doc/ directory.

Fixes: #353


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3299 d4fa192b-c00b-0410-8231-f00ffab90ce4

ChangeLog

+
+Please note that this file is no longer maintained.  Please refer to the
+changes files in doc/
+
 Change log for Varnish 1.0.4
 
 Changes between 1.0.3 and 1.0.4