Missing Participating Media Type

[Xaldew]

Hello!

I was looking through the documentation for participating media for PBRTv3 and PBRTv4 the other day, and noticed that the second scene description example looks wrong:

MakeNamedMedium "mymedium" "homogeneous" "rgb sigma_s" [100 100 100]
MediumInterface "" "mymedium"

Looking at the PBRT code itself, I believe there's a missing "string type" before the "homogeneous", for both the v3 and v4 documentation.

Link references:
V3: https://www.pbrt.org/fileformat-v3#media-world
V4: https://www.pbrt.org/fileformat-v4#media-world