This patch updates our docs to include some details on the 'inherit'
segmentation type supported by trunk subports. The API is updated in
I0772463d71cbb6703345e66f52ad6c02163a00ff.
Change-Id: I9bebf8a3543bff43cf6e80a0d4523b0c9b5c6eb5
Closes-Bug: #1679999