development(7): Replace "reboot" with "shutdown -r now"

We generally document shutdown(8) instead of reboot(8) as it's better for
interactive use.

In modern FreeBSD is matters a lot less, it's mostly just convention. One
minor thing is that shutdown(8) produces a global message, while reboot(8)
does not. It is believed that historically, some versions of reboot did not
do appropriate safe shutdown checks and just rebooted.

It's also just consistency: for example the handbook[1] documents shutdown.

There is actually another important difference between reboot and shutdown
-r now: reboot does not run /etc/rc.shutdown. This is because reboot has
its own shutdown procedure and does not signal init like init 6 and
shutdown -r now do (except in the case of rerooting via reboot -r).

A few years ago jilles@ proposed changing reboot's default to signalling
init (preserving reboot -q which just invokes the reboot system call), but
this was not accepted. Perhaps this can be tried again for 13.0.

[1]: https://www.freebsd.org/doc/handbook/boot-shutdown.html

Reported by:	eadler
Reviewed by:	eadler, jilles
Approved by:	krion (mentor)
Differential Revision:	https://reviews.freebsd.org/D16843

share/man/man7/development.7

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 22, 2018
+.Dd November 16, 2018
 .Dt DEVELOPMENT 7
 .Os
 .Sh NAME
@@ -110,7 +110,7 @@ system:
 svnlite co https://svn.FreeBSD.org/base/head src
 cd src
 make -j8 buildworld buildkernel installkernel
-reboot
+shutdown -r now
 .Ed
 .Pp
 After reboot: