Update IfcWallTypeEnum.md

[MennoMekes]

since STANDARD will be deprecated, there do not seems to be a place for gypsum-block walls and other light weight partitioning walls. PARTITIONING is now described as a light-weight, sandwich construction. I think the massive non-loadbearing walls should be included as well. This is not a change, just an addition to the description.

[Moult]

Agreed, architects usually classify walls into things like:

• partitions
• masonry (block walls, brick walls)
• exterior walls (i know, there's an overlap with IsExternal)
• core walls
• riser / service walls
• intertenancy walls

These are a mixed bag of classifying by purpose, area, and material, but despite the messiness it has definite value to people. E.g. core walls are extremely significant for structure, 4d, 5d. Partition vs masonry are two different trades and details, etc.