nsmb.conf(5): Document the order of configuration loading

Based on the comments in /etc/nsmb.conf.

Reviewed by:	bcr
Approved by:	krion (mentor, implicit), mat (mentor, implicit)
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D17810

share/man/man5/nsmb.conf.5

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 24, 2016
+.Dd November 2, 2018
 .Dt NSMB.CONF 5
 .Os
 .Sh NAME
@@ -41,6 +41,21 @@ or mount points for the
 .Tn SMB
 network protocol.
 .Pp
+The configuration files are loaded in the following order:
+.Pp
+.Bl -enum -offset indent -width "" -compact
+.It
+.Pa ~/.nsmbrc
+.It
+.Pa /etc/nsmb.conf
+.El
+.Pp
+As a result,
+.Pa /etc/nsmb.conf
+settings
+override those in
+.Pa ~/.nsmbrc .
+.Pp
 The configuration hierarchy is made up of several sections,
 each section containing a few or several lines of parameters
 and their assigned values.