New comment by Chocimier on void-packages repository

https://github.com/void-linux/void-packages/pull/26883#issuecomment-739317579

Comment:
`make_*_target` needs documentation, as they are used a bit different than in make-based build styles.
Add new build style to _build style scripts_ section too.
Please do not reformat existing manual sections when they stay with same content. Minimal, meaningful diffs are good.