Hi @ChipG, @JimBo has provided the answer.
Google recently updated their UI to change the way their third-party integrations are added. Once your Google Home has been linked to your account, you simply need to:
1) Open the Google Home app
2) Swipe right to access the sidebar
3) Select Explore
4) Select 'Home Control'
5) Browse for the Rachio app
6) Link your account
7) Proceed with commands
Hope this helps! We're working on updating the Support article with the recent changes. Huge shoutout to @JimBo again!