Minor mdoc fixes.

usr.sbin/bsdconfig/bsdconfig.8

@@ -129,7 +129,7 @@ Generate a graphviz
 language file
 .Pq printed on stdout
 visualizing the
-.Xr bsdconfig 8
+.Nm
 menu, include, and shortcut structure and relationships.  See
 .Dq bsdconfig dot -h
 for more details.

usr.sbin/chroot/chroot.8

@@ -60,7 +60,7 @@ options are given,
 the user,
 group and group list of the process are set to
 these values after the
-.Xr chroot 8
+.Nm
 has taken place.
 .Sh ENVIRONMENT
 The following environment variable is referenced by

usr.sbin/mountd/exports.5

@@ -101,7 +101,7 @@ This line does not export any file system, but simply marks where the root
 of the server's directory tree is for NFSv4 clients.
 The exported file systems for NFSv4 are specified via the other lines
 in the
-.Xr exports 5
+.Nm
 file in the same way as for NFSv2 and NFSv3.
 The pathnames must not have any symbolic links in them and should not have
 any