Range of Documentation Updates

[dmason1992]

Page 17 – M3x5mm SHCS (12 screws or 16 screws?)
Page 18 – M3 heatset inserts (what size? LDO send two different M3 lengths)
Page 20 – M3 heatset inserts (what size? LDO send two different M3 lengths)
Page 28 – Spacing for Rails? (noted about butting it against the Idler end)
Page 46 – 2080 or 2040?
Page 60 – LDO has different C extrusion lengths? (320,320,25,120)
Page 68 – Missing step for screwing the linear rails