man: de-duplicate AUTHOR/BUGS sections

man: de-duplicate AUTHOR/BUGS sections

Move the sections into a dedicated trailer.scd file, which gets added
during manpage generation.

Note, that this removes the following text from kmod.8, which is
intentional:

*kmod* project was started by Lucas De Marchi as a drop-in replacement to
module-init-tools that was maintained by Jon Masters, adding a library (libkmod)
and additional features.

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>