Correct usage for parentheses, and mark up "expression" in more places.

From Bug Hunting in PR 42286.

bin/test/test.1

@@ -1,4 +1,4 @@
-.\"	$NetBSD: test.1,v 1.26 2009/05/06 08:26:43 wiz Exp $
+.\"	$NetBSD: test.1,v 1.27 2009/11/10 18:19:46 wiz Exp $
 .\"
 .\" Copyright (c) 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -32,7 +32,7 @@
 .\"
 .\"     @(#)test.1	8.1 (Berkeley) 5/31/93
 .\"
-.Dd May 5, 2009
+.Dd November 10, 2009
 .Dt TEST 1
 .Os
 .Sh NAME
@@ -47,17 +47,24 @@
 .Sh DESCRIPTION
 The
 .Nm test
-utility evaluates the expression and, if it evaluates
+utility evaluates
+.Ar expression
+and, if it evaluates
 to true, returns a zero (true) exit status; otherwise
 it returns 1 (false).
-If there is no expression, test also
+If
+.Ar expression
+is not given,
+.Nm test
+also
 returns 1 (false).
 .Pp
 All operators and flags are separate arguments to the
 .Nm test
 utility.
 .Pp
-The following primaries are used to construct expression:
+The following primaries are used to construct
+.Ar expression :
 .Bl -tag -width Ar
 .It Fl b Ar file
 True if
@@ -269,8 +276,10 @@ True if either
 or
 .Ar expression2
 are true.
-.It Cm \&( Ns Ar expression Ns Cm \&)
-True if expression is true.
+.It Cm \&( Ar expression Cm \&)
+True if
+.Ar expression
+is true.
 .El
 .Pp
 The
@@ -300,10 +309,11 @@ The
 utility exits with one of the following values:
 .Bl -tag -width Ds
 .It 0
-expression evaluated to true.
+.Ar expression
+evaluated to true.
 .It 1
-expression evaluated to false or expression was
-missing.
+.Ar expression
+evaluated to false or was missing.
 .It \*[Gt]1
 An error occurred.
 .El