Add development documentation on separating Redis workloads
In &462 (closed), we learned a lot about adding a new Redis instance to take a vertical slice of work away from another instance.
In &526 (closed), we are doing this process again.
Before we start the new issue, we should look at how we structured the previous epic and condense that into some development guidelines in our documentation. This will:
- Help inform the structure of this project.
- Give us a place to add things we learn from this project.
- Give us a clearer starting point for future slices (like sessions).