Documentation: 80T Pulley centering instructions

[k1-801]

As of now, the 80T pulley installation page for ERCF (page 29) simply shows to install the 20T pulley inside of it and tighten the 5 screws. Unfortunately, no matter how hard I tried, I failed to ensure the concentricity of the bigger pulley with the smaller one - and, by that, with the D-shaft. Even tightening them by a star pattern, going half thread at a time, makes the assembly offset from the center, with the very first screw that went in pushing the 20T pulley away from the center on the very first half a thread that it went in and the other 4 screws not pushing it back. The drawback in this scenario is not only the belt tension changing, but the pulley rubbing against the motor arm with non-negligible amount of friction in some stages of the D-shaft's rotation.

If there is a good technique to assemble this without it running off-center, it would be best to put it on the documentation page.