pw.conf: Describe better + tag SPDX

MFC after:		3 days
Reported by:		Artem Bunichev <[email protected]>
Differential Revision:	https://reviews.freebsd.org/D58329

usr.sbin/pw/pw.conf.5

@@ -1,3 +1,6 @@
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
 .\" Copyright (C) 1996
 .\" David L. Nugent.  All rights reserved.
 .\"
@@ -22,12 +25,12 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 30, 2007
+.Dd September 8, 2026
 .Dt PW.CONF 5
 .Os
 .Sh NAME
 .Nm pw.conf
-.Nd format of the pw.conf configuration file
+.Nd system user and group editor configuration file
 .Sh DESCRIPTION
 The file
 .Pa /etc/pw.conf