man: remove outdated COPYRIGHT section

man: remove outdated COPYRIGHT section

While the section is fairly common (11.9k instances of 27.5k man pages
in my Arch install) it is not as ubiquitous as the rest.

Furthermore, the information is severely outdated.

Just remove it all together, instead of trying to devise some clever way
of managing it.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Lucas De Marchi <demarchi@kernel.org>
Link: https://github.com/kmod-project/kmod/pull/pull/400
Signed-off-by: Lucas De Marchi <demarchi@kernel.org>