how to provide redundancy with setting up client not clear

A user says they could not determine how to set up the PHP client for failover per the docs. I think that means there is confusion about what is actually happening when setting up the URLs.

From the user:
i didn't find anything in the examples about adding multiple servers kelye @ 2:19
like new Couchbase ('10.1.1.1:1121, 10.1.1.2:1121'. .. etc 2:19
for failover 2:19

I've explained things, but perhaps we need to do more at the documentation level?