Documentation for realtime.roblox.com?

Hello, is there any documentation for the realtime.roblox.com endpoint?
Right now, all I know is that it’s a websocket, I’m looking to see whether there is any documentation or community documentation out there.

Thank you

https://realtime.roblox.com/notifications/start
https://realtime.roblox.com/notifications/negotiate

I already have these endpoints. I’m unsure how to use them correctly, I’ve started looking at the requests being sent but the furtherest I’ve got is getting a sucessful negotiation with the /negotiate endpoint but attempting to use /start, I’m met with a HTTP 400 status code and a body of The ConnectionId is in the incorrect format.