Extend the reliability of ST38 and AM14LS

For racing at tracks with hard boards, which are common in US for example, we recommend to add following "TECH TIP" to extend the reliability of ST38 and AM14LS.

Following parts are needed for this mod:
- 4x SH1.0
- 2x AT21 (AT21S/AT21ST-A are alsio suitable)
- 2x SB3x6

By installing the SB3x6 screw with one SH1.0 below and above AM14LS and secruing the shim on top with AT21, the strength of the steering arm is increased for more reliability in this particular area.

Furthermore the AT21 on top will be another steering limiter in crash situations. Especially at hitting the plastic track barriers with the wheel axles, a pretty high force can be applied to the suspension which cause high load on the steering arm and ST38 drive shaft nuts.
With AT21 as "emergency stopper" (beside AT18 steering limiter) this force can be reduced and limited.