Fix markup errors.

external/bsd/byacc/bin/yacc.1

@@ -1,4 +1,4 @@
-.\"	$NetBSD: yacc.1,v 1.7 2018/07/24 05:40:15 wiz Exp $
+.\"	$NetBSD: yacc.1,v 1.8 2020/07/26 23:18:06 uwe Exp $
 .\"
 .\" Copyright (c) 1989, 1990 The Regents of the University of California.
 .\" All rights reserved.
@@ -32,7 +32,7 @@
 .\"
 .\"	from: @(#)yacc.1	5.7 (Berkeley) 7/30/91
 .\"	from: Id: yacc.1,v 1.24 2014/10/06 00:03:48 tom Exp
-.\"	$NetBSD: yacc.1,v 1.7 2018/07/24 05:40:15 wiz Exp $
+.\"	$NetBSD: yacc.1,v 1.8 2020/07/26 23:18:06 uwe Exp $
 .\"
 .Dd October 5, 2014
 .Dt YACC 1
@@ -424,7 +424,7 @@ in this array.
 .El
 .Sh PORTABILITY
 According to Robert Corbett:
-.Bd -offset indent
+.Bd -filled -offset indent
 Berkeley Yacc is an LALR(1) parser generator.
 Berkeley Yacc has been made as compatible as possible with AT\*[Am]T Yacc.
 Berkeley Yacc can accept any input specification that conforms to the
@@ -475,7 +475,7 @@ delete that directive.
 .Pp
 .Xr bison 1
 no equivalent for some of
-.Nm 's
+.Nm Ns 's
 command-line options, relying on directives embedded in the grammar file.
 .Pp
 .Xr bison 1
@@ -522,7 +522,6 @@ but
 for destructors.
 .Nm
 matches this behavior.
-.El
 .Sh ENVIRONMENT
 The following environment variable is referenced by
 .Nm :