nfsv4.4: Update and add a new NFSv4 ROOT section

[rmacklem]

Summary

Recent commits added support for a NFSv4 root
file system.

This patch adds a section to nfsv4.4 that explains
the setup for an NFSv4 ROOT file system.

It also updates some of the other information.

[kib]

usr.sbin/nfsd/nfsv4.4

167–169

BTW, is the use of 'server' there means the nfs server specifically? Is the nfsuserd still needed on the client?

326

Is this functionality still present? If yes, IMO we should not remove the docs. The introductory part of the paragraph discourage its use already.

396

405

Or
.Xr fstab 5

408

422

Perhaps just say that this sysctl MIB needs to be set, instead of referencing some config.

430

441

.Ql

[rmacklem]

I think I covered kib@'s inline comments.

I had used `` and '' for consistency, but I've now
changed all occurrences of them to .Ql.

[rmacklem]

usr.sbin/nfsd/nfsv4.4

422

When this happens matters.
By putting the entry in /etc/sysctl.conf,
it happens soon enough. If it doesn't
happen soon enough, you get "not owned
by root" and cannot login once it is multiuser.
(You get "could not determine audit condition".)
This is irritating, because even the google AI has
no idea why it happens.

As such, I specifically say "stick it in /etc/sysctl.conf".

441

I made all the `` '' .Ql's.

[kib]

usr.sbin/nfsd/nfsv4.4

422

The comment in response to my question is more informative than the man page. I suggest to explain that in the man: mention that the sysctl MIB needs to be set early, before <something>, Then you could state that the most straightforward way to do it is to set it in sysctl.conf.

[rmacklem]

Added a sentence w.r.t. when vfs.nfs.enable_uidtostring
needs to be set, as suggested by kib@.