seccomp_unotify.2: Document SECCOMP_ADDFD_FLAG_SEND
This flag was recently added to Linux 5.14 by a patch I wrote:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=
0ae71c7720e3ae3aabd2e8a072d27f7bd173d25c
This patch adds documentation for the flag, the error code that the flag
added and explains in the caveat when it is useful.
Signed-off-by: Rodrigo Campos <rodrigo@kinvolk.io>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>