Not quite a booklet but a warning label, as Abasmajor suggests. It warned owners not to adjust the trigger pull weight too light as that could result in a negligent discharge.
The Mk 11 originally came with a folded sheet, which advertised the pistol's best features. Coincidentally mine must have been exported to the States and back again as prices are in U.S. $. I obtained it from Troubledshooter and a scan may well be included on his excellent signature site.
Mk 1 and Mk 11 pistols were numbered concurrently from the same serial number range and the earliest number known to me presently is 10105, which was pictured in the June 1978 issue of Guns Review by Mark Newcomer.
I think you will enjoy the Gordon Bruce book.
Kind regards,
John