Instructions for how to renew?

@Osiris looking at a renewal notice I got recently, it also included this paragraph:

We recommend renewing certificates automatically when they have a third of their
total lifetime left. For Let's Encrypt's current 90-day certificates, that means
renewing 30 days before expiration. See
Integration Guide - Let's Encrypt for details.

I'm not sure why that isn't aligned with the version in git.