Margin is wrong on Deskjet 3760

The PPD file DeskJet_3700.ppd gives a wrong margin on DeskJet 3760, resulting in image truncation.

According to the official support (https://h30434.www3.hp.com/t5/Printing-Errors-or-Lights-Stuck-Print-Jobs/Why-doesn-t-my-new-hp-deskjet-3760-print-photos-on-A4-up-to/td-p/7222350), the margins are 3 mm, 3 mm, 3 mm and 12.7 mm for left, right, top and bottom.

Therefore the ImageableArea line for A4 should say
*ImageableArea A4/A4 210x297: "8.39999961853 41.1023622047 587.039978027344 833"
which fixes my problem on my printer.

Related question: https://answers.launchpad.net/hplip/+question/667437