I've noticed there's a SignalR.SqlServer class on github. https://github.com/paigecook/SignalR/tree/master/SignalR.SqlServer
Wondering if I can use it to listen for database updates and send them to the client? If yes, is there any documentation/examples on this feature?
No you can't. This is an implementation of SignalR's IMessageBus on top of SQL Server. It allows you to use SignalR in a webfarm, using Sql server as the backplane to communicate messages to all webnodes.