Update SELinux-sctp.rst "SCTP Peer Labeling" section to reflect
how the association permission is validated.
Reported-by: NDominick Grift <dac.override@gmail.com>
Signed-off-by: NRichard Haines <richard_c_haines@btinternet.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>