Fix docs for 1.7/1.8 3DSceneLayer mandatory/optional properties

[ladislavhorky]

Hello,

with last update of ArcGIS Pro to version 3.1.0 we are no longer able to open integrated mesh SLPKs we created with our SW following the documentation here on GitHub. ArcGIS will not provide any actionable error short of "cannot repair resource". Running fresh i3s_converter.exe -v gives some hint that layer.geometryDefinitions length needs to be at least 1 while we have 0 (we do not include this property at all). This suggests the geometryDefinitions are now mandatory.

geometryDefinitons are clearly stated to be optional (not bold) in both 1.7 and 1.8 docs:
https://github.com/Esri/i3s-spec/blob/9f6c4e8795b6a25fecc89fadd0288ba353ac7b6e/docs/1.8/3DSceneLayer.cmn.md

Could you please revise the docs to make it match with what is actually mandatory and what is not?

[Ivonne-S]

Our apology for not stating the documentation fix of geometryDefinition clearly. In the latest documentation we did fix it here. https://github.com/Esri/i3s-spec/blob/master/docs/1.8/3DSceneLayer.cmn.md

[ladislavhorky]

Thanks! We will try to test in a while and let you know if this was the only thing (as it looks from the fixed doc).