Create and document renovate configs for Rancher Projects to use #56
Description
Per title, this is to track creating Renovate Config and documenting it as an example.
This is specifically to help address issues like this renovate PR: rancher/backup-restore-operator#683
The issue is that each "Project Branch" targeting a specific Rancher Minor should only target the Kuberlr-kubectl image that matches the Minor version of Rancher.