Update several URLs pointing to https://www.debian.org/doc/debian-policy to match the new URLs since debian-policy 4.1.0.

This is work in progress, this commit changes:

sed "s|https://www.debian.org/doc/debian-policy/#configuration-files|https://www.debian.org/doc/debian-policy/ch-files.html#configuration-files|g

"

Signed-off-by: Holger Levsen <holger@layer-acht.org>