Better document the relationship between persist, commit, and permits #1689
Description
This wasn't clear from a casual read of the persist worker.
nit: Not directly related to this PR, but the relationship between commits, persists, and permits is not very clear. The purpose of the semaphore is the control the rate of commits. Does a permit allow one to commit, and a persist of a batch of commits will then release multiple permits?
Originally posted by @bernard-avalabs in #1685 (comment)