rc.subr: improve description for ${name}_offcmd

Clarify that ${name}_offcmd is for method start.

MFC after:	3 days

libexec/rc/rc.subr

@@ -982,7 +982,8 @@ startmsg()
 #
 #	${name}_limits	n	limits(1) to apply to ${command}.
 #
-#	${name}_offcmd	n	If set, run if a service is not enabled.
+#	${name}_offcmd	n	If set, run during start
+#				if a service is not enabled.
 #
 #	${rc_arg}_cmd	n	If set, use this as the method when invoked;
 #				Otherwise, use default command (see below)

share/man/man8/rc.subr.8

@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd June 2, 2024
+.Dd June 18, 2024
 .Dt RC.SUBR 8
 .Os
 .Sh NAME
@@ -774,7 +774,7 @@ Login class to use with
 Defaults to
 .Dq Li daemon .
 .It Va ${name}_offcmd
-Shell commands to run if a service is not enabled.
+Shell commands to run during start if a service is not enabled.
 .It Va ${name}_oomprotect
 .Xr protect 1
 .Va command