Confusion about the `CommodityType` parameter

The [documentation for this parameter](https://muse-os.readthedocs.io/en/latest/inputs/commodities.html) states that "Service" should be used for end-use commodities such as heating, however the example models/tutorials use "Energy" for the `heat` and `cook` commodities. This is confusing and needs to be clarified.

Looking at the code, "Energy" and "Environmental" are the only `CommodityType` options that are directly referenced. For end-use commodities, the important thing is that they get picked up by the `is_enduse` function, but this will be true for any products that are not the "Environmental" type (so it doesn't actually matter if it's "Service" or "Energy")