Mk: depulicate WWW information

Stop duplication the WWW informations within the packages

Since september 2022 the WWW lines has been moved from pkg-descr
to Makefile, however the ports tree continued to push this info
at the end of pkg-descr automatically, which is a duplicated
information.

Differential Revision: https://reviews.freebsd.org/D41523
Reviewed by: mat