Example on using aiomcache for a cluster

Thanks for building this amazing lib!
I was wondering if you can share an example for using `aiomcache` to connect to a memcached cluster with more than one host?

Seems like [this](https://github.com/aio-libs/aiomcache/blob/0f527db6660c6ce5e6c40ae806f2e8cfe624a894/aiomcache/pool.py#L72) is how connection are established and I don't see any other source code for connection management for multi-node cluster. Given how widely memcached clusters are used, I think an example would be really helpful