Eliminate a groff warning. Clarify text.

share/man/man4/sn.4

@@ -27,9 +27,9 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\"	$NetBSD: sn.4,v 1.1 2007/06/20 13:31:55 tsutsui Exp $
+.\"	$NetBSD: sn.4,v 1.2 2009/05/17 02:36:10 fair Exp $
 .\"
-.Dd June 20, 2007
+.Dd May 16, 2009
 .Dt SN 4
 .Os
 .Sh NAME
@@ -108,7 +108,7 @@ These messages indicate that the interface gets errors
 The
 .Nm
 interface for mac68k, which was derived from a driver for old
-.Nx pica
+.Nx Ns /pica
 port, first appeared in
 .Nx 1.3 .
 .Pp
@@ -118,7 +118,11 @@ and
 .Xr bus_space 9
 APIs after
 .Nx 1.5
-release, and arc has been switched to using the MI driver.
-mac68k has been also switched to using the MI driver after
+release, and
+.Nx Ns /arc
+has been switched to using the machine independent (MI) driver.
+.Pp
+.Nx Ns /mac68k
+has also been switched to using the MI driver after the
 .Nx 4.0
 release.