RT-28746 Need to tighten the specification to restrict the value for face smooth group from 0 to 31

[Kevin Rushforth]

The restriction of 32 unique smoothing groups was already there. This is 
just documenting and validating that restriction.

-- Kevin


August Lammersdorf, InteractiveMesh wrote:
> - Which releases will be affected by this restriction?
>
> - What are the reasons?
>
> Thanks, August