You should submit it to Martin....Is the manual wrong? A typo?
Please confirm this...
My guess is that it's an oversight inherited from Orbiter2010's Deltaglider.pdf doc, where at page 5 you can read:
CTRL+B - Deploy/retract airbrakes
But at those times DG's airbrake actuation was a long, one-step movement.
When Martin introduced the two-steps deployment, he eventually forgot to update the instructions.