Copy stable/11@r303970 to releng/11.0 as part of the 11.0-RELEASE
cycle.

Prune svn:mergeinfo from the new branch, and rename it to RC1.

Update __FreeBSD_version.

Use the quarterly branch for the default FreeBSD.conf pkg(8) repo and
the dvd1.iso packages population.

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

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Fix various mdoc issues.

Found with: mandoc -Tlint

use .Mt to mark up email addresses consistently (final part)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

mdoc: Avoid playing tricks with Ns: If Nm is present in the SYNOPSIS section,
it will be output on its own line. Ns cancels this effect however. This change
is also consistent with the rest of our manual pages.

mdoc: drop redundant .Pp and .LP calls

They have no effect when coming in pairs, or before .Bl/.Bd

Manual page for the kernel side Secure Neighbor Discovery support.

Reviewed by: brueffer
Approved by: bz (mentor)