Rework the details about the IEEE OpenGroup Press Release for letting
the FreeBSD Project Incorporate Material from the POSIX standard.

The OpenGroup have made a Press Release, point to that URL instead of
the one by BusinessWire.

Note, the article by BusinessWire is still archived; simply because
it does not hurt to have it lay around.

Suggested by: Ruslan Ermilov <ru at freebsd.org>