Fix typo in comment.

Masahiko Sawada

src/bin/pg_rewind/RewindTest.pm

@@ -183,7 +183,7 @@ sub promote_standby
 	  or die "Timed out while waiting for promotion of standby";
 
 	# Force a checkpoint after the promotion. pg_rewind looks at the control
-	# file todetermine what timeline the server is on, and that isn't updated
+	# file to determine what timeline the server is on, and that isn't updated
 	# immediately at promotion, but only at the next checkpoint. When running
 	# pg_rewind in remote mode, it's possible that we complete the test steps
 	# after promotion so quickly that when pg_rewind runs, the standby has not