Bug#601408: developers-reference: Document UNRELEASED value for Distribution field

[anatoly <techtonik@php.net>]

Package: developers-reference
Severity: important

UNRELEASED is not listed among allowable Distribution values in .changes file.
http://www.debian.org/doc/manuals/developers-reference/pkgs.html#distribution

-- System Information:
Debian Release: 5.0.5
  APT prefers stable
  APT policy: (990, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.26-2-686-bigmem (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash