Documentation on crons should cover how the jobs are run across the cluster

[hguthrie]

Description

I think the DevDocs should cover how cron execution is split across the server cluster. My understanding is as follows (I'm only really interested in / aware of Pro production)

On a traditional 3 server cluster the crons can be executed on any given node and are distributed across the cluster
In a scaled environment, crons are executed on the three non-web nodes and are distributed across those nodes
It seems like how this works should be documented here, so calling this out as a gap as I couldn't find any info on it.

This seems like a logical home for this info: https://devdocs.magento.com/cloud/configure/setup-cron-jobs.html

Content checklist

Additional information

Issue moved from magento/devdocs#9384