contacts: ensure full deletion in +do-edit

This was repeatedly deleting from the outer value, instead of the accumulator intended to replace it.

This would result in only a single key being deleted, even if an edit specified multiple keys for deletion.

desk/lib/contacts.hoon

@@ -244,7 +244,7 @@
   =?  don  !=(~ del)
     %+  roll  del
     |=  [key=@tas acc=_don]
-    (~(del by don) key)
+    (~(del by acc) key)
   don
 ::  +from-0: legacy to new type
 ::