User testing and docs for new M3 motor mounting

!448 (merged) needed merging as it was getting so big. It is tested, but as a larger change needs more testing and documentation review before we can release.

Finalise hardware:

• Clear hole for optics fitting screw (!448 (comment 2597532073)). Applied in !469 (merged)
• Fix cut-outs on z-axis for Manual to remove residual thin casing. Applied in !471 (merged)
• Fix illumination mount screw nut slot angle to avoid the larger z-motor screw cut-outs. Applied in !470 (merged)
• Get this version on the community forum and build in 2-3 locations

Do a full check through of the relevant documentation sections: Applied in !474 (merged)

• Motor nuts are included in prepare main body and prepare separate z-actuator
• Motor nuts not included for Manual
• Motor nuts follow through into all later renders and GLBs as required
• Add motor nut insertion to the prepare separate z- actuator .md page