services.5: describe better

Use a more specific description for this man page, and add SDPX tag
while here.

Reviewed by:	imp, meena
Signed-off-by:	Alexander Ziaee <concussious@runbox.com>
Pull Request:	#1194

share/man/man5/services.5

@@ -1,3 +1,6 @@
+.\"-
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
 .\" Copyright (c) 1983, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
 .\"
@@ -25,12 +28,12 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 4, 2010
+.Dd April 29, 2024
 .Dt SERVICES 5
 .Os
 .Sh NAME
 .Nm services
-.Nd service name data base
+.Nd internet service name and port number data base
 .Sh DESCRIPTION
 The
 .Nm