address horizontal scalability in documentation

[srsudar]

Part of the documentation?
I’ve read the following page of the documentation …

• Scalability
• Cloud
• homepage, where it says "Scales with Redis: Spin up multiple instances and keep them in sync with Redis, or even Redis clusters."

Really helpful parts
I think this part is really good: …

(lots of good detail in general)

Hard to understand, missing or misleading
But you really need to improve …

It's not clear to me the guarantees hocuspocus tries to achieve around horizontal scaling. #178 and #279 both talk about horizontal scaling, but I'm hoping for something explicit in the code that yes, hocuspocus supports multiple instances behind a load balancer, if all features (eg stateless messaging) are expected to work, etc. I think the answer is yes, but I'd love more explicit confirmation somewhere!

Additional context
Add any other context or screenshots here.