[2.0.21] LuaEntity::temperature does not mention heat pipes

[Quezler]

https://lua-api.factorio.com/latest/cla ... emperature

> The temperature of this entity's heat energy source. nil if this entity does not use a heat energy source.

heat pipes have no energy source (neither in data.raw or prototype explorer) but it still returns the temperature, which does not match the description.

[Bilka]

Thanks for the note, I've added more information on entities with heat buffers to the docs for the next release.