Fix a typo in a section header.

reservations.scrbl

@@ -115,7 +115,7 @@ You may have more than one reservation at a time; if you need resources of
 more than one type, or on different clusters, you can get this by requesting
 mutliple reservations.
 
-@section[#:tag "reservations-making"]{Using a Reservation}
+@section[#:tag "reservations-using"]{Using a Reservation}
 
 To use a reservation, simply create experiments as normal. Experiments run
 during the duration of the reservation (even those begun before its start