- rename the RETURN VALUES section to EXIT STATUS [1]

- convert to .Ex macro
- not bumping a date as this is not a real content change

Approved by:	ru [1]
MFC after:	3 days

usr.sbin/rtadvd/rtadvd.8

@@ -162,10 +162,8 @@ In this case,
 will transmit router advertisement with router lifetime 0
 to all the interfaces
 .Pq in accordance with RFC2461 6.2.5 .
-.Sh RETURN VALUES
-The
-.Nm
-program exits 0 on success, and >0 on failures.
+.Sh EXIT STATUS
+.Ex -std
 .Sh FILES
 .Bl -tag -width Pa -compact
 .It Pa /etc/rtadvd.conf