Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix typos, spelling, formatting and mdoc mistakes found by Nobuyuki while
translating these manual pages. Minor corrections by me.

Submitted by: Nobuyuki Koganemaru <n-kogane@syd.odn.ne.jp>

Fix typos and spelling mistakes.

Fix typo and remove extra spaces.

Approved by: rrs (mentor)
MFC after: 3 days

Fix the cross-reference to sctp_opt_info in the text - section 3, not 2.

PR: 140938
Submitted by: Bruce Cran <bruce@cran.org.uk>
MFC after: 2 weeks

- Use the correct expanded name for SCTP (1)
- Remove empty section

PR: 116496 (1)
Submitted by: koitsu
Approved by: re (blanket)

Fix include declaration it was sys/sctp.h should be netinet/sctp.h,
reported by pluknet@gmail.com.

First cut of the sctp man pages. Still need work.