grammar bit

<Someone> wrote:
> You find an anti-magic field.
> Where do you want to jump?  (For instructions type a ?)
> You pass right over _a_ anti-magic field.

doc/fixes34.4

@@ -219,6 +219,7 @@ create_object() created lizard corpses without timers and troll corpses with
 	their revive timers, then changed the corpsenm field
 when a potion of acid was dropped into water and exploded, nethack would
 	continue to use already freed memory and later might panic or crash
+when jumping over an already seen trap, use an() to get appropriate grammar
 
 
 Platform- and/or Interface-Specific Fixes