apropos(1): Tweak the description of -1, ... -9, and -s

-s is not for compatibility only, because section names can be
anything.  E.g. we have 3lua and 9lua in base.  We have rudiments of
3f (for FORTRAN libs).  Some packages in pkgsrc also use suffixed 1
and 3 sections.

usr.sbin/makemandb/apropos.1

@@ -1,4 +1,4 @@
-.\" $NetBSD: apropos.1,v 1.21 2022/05/17 08:39:58 uwe Exp $
+.\" $NetBSD: apropos.1,v 1.22 2022/05/17 11:31:14 uwe Exp $
 .\"
 .\" Copyright (c) 2011 Abhinav Upadhyay <er.abhinav.upadhyay@gmail.com>
 .\" All rights reserved.
@@ -63,8 +63,12 @@ Quotes are optional for specifying multiword queries.
 .Pp
 It supports the following options:
 .Bl -tag -width Fl
-.It Fl [1-9]
-Search only within the specified section of manual pages.
+.It Fl 1 , No \&... , Fl 9
+Limit the search to the specified section of the manual.
+By default, pages from all sections are shown.
+These options are abbreviations for the
+.Fl s
+option for single digit sections.
 .It Fl C Ar path
 Use different
 .Xr man 1
@@ -95,12 +99,10 @@ Turn off formatting.
 Limit the search to the pages for the specified machine architecture.
 By default pages for all architectures are shown in the search results.
 .It Fl s Ar section
-Restrict the search to the specified section of the manual.
+Limit the search to the specified section of the manual.
 By default, pages from all sections are shown.
-This option is for backwards compatibility with the classic version of apropos,
-using it is equivalent to using the
-.Op 123456789
-options directly.
+For single digit sections you can use abbreviations:
+.Fl 1 , No \&... , Fl 9 .
 .El
 .Sh FILES
 .Bl -hang -width /etc/man.conf -compact