That is your front axle pivot adjustment.
"If front axle pivot pin adjustment is not correct, front wheel vibration can occur causing vibration in the steering wheel"
Adjusting procedure - Loosen the lock nut, tighten the adjusting screw (tightening torque 20 N-m, 2.0 kgf-m, 15 ft lbs), then loosen the screw by 1/6 turn. Re tighten the lock nut.
Page 64 of your manual