rc.8: Reference the article about rc scripting

MFC after:	3 days

share/man/man8/rc.8

@@ -31,7 +31,7 @@
 .\"     @(#)rc.8	8.2 (Berkeley) 12/11/93
 .\" $FreeBSD$
 .\"
-.Dd October 6, 2020
+.Dd July 4, 2022
 .Dt RC 8
 .Os
 .Sh NAME
@@ -573,6 +573,11 @@ is unnecessary, but is often included.
 .Xr savecore 8 ,
 .Xr service 8 ,
 .Xr sysrc 8
+.Pp
+.Rs
+.%T "Practical rc.d scripting in BSD"
+.%U "https://docs.freebsd.org/en/articles/rc-scripting/"
+.Re
 .Sh HISTORY
 The
 .Nm