New review comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/23515#discussion_r453209823

Comment:
The helper adds the deps where they are necessary and not already provided by the template. I've been meaning to add a description of the new helper in the manual and will push that later today.

Maybe the host/target dependency issue for Python could use some specific attention in the manual, but that is more general and belongs in a separate PR. I'll give it some thought and put something together later.