ParameterGroup description should be listed as optional

[SpeckledFleebeedoo]

The description field for a ParameterGroup in the runtime docs json API is not listed as optional but is not present for a number of them, so it should probably be listed as optional. The first example I ran into was on LuaControl::set_gui_arrow.

Alternatively, for consistency, it may be better if these are given descriptions in the API, as currently the ParameterGroups are the only types in the API that may lack descriptions.

[Therenas]

Thanks for the thread. These were not intended to be missing, but instead just empty strings if need be, like other descriptions as you pointed out.

This will be fixed with the next release (sort of as a byproduct of other format changes). Might be a bit until the release though.