Drain and extra-day legs always trade MNQ

They traded the micro of whatever the firm listed: MNQ with NQ, but MGC
for a firm listing only GC and CL. Now every futures firm's tiny legs go on
MNQ, the one micro the bot has always drained on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -122,8 +122,7 @@ the batch firm's list, at random but weighted:
   the type's max contracts); an instrument whose expected hold for the
   batch's leg is 12 h or more is out of the draw (e.g. 6E at a $1,000 leg,
   about a week).
-- Micros stay out of the draw; drain and extra-day legs trade the micro of a
-  listed product (MNQ when NQ is listed).
+- Micros stay out of the draw; drain and extra-day legs always trade MNQ.
 
 Every draw logs its odds. `GET /api/instruments` shows each firm's list with
 spread, daily move, hold and chance (`?simulate=10000` runs the real draw