Three Server Cluster Example - cluster port

[sishanks]

Re: https://github.com/nats-io/nats.docs/blob/master/running-a-nats-service/configuration/clustering/README.md

'Three Server Cluster Example' instructions don't appear to work. Looks like its due to incorrect port on 1st server command.

Details:

In the 'Three Server Cluster Example' section it starts with
nats-server -p 4222 -cluster nats://localhost:5222 -D
this looks like it should be
nats-server -p 4222 -cluster nats://localhost:4248 -D
(wrong cluster port)

It looks like it doesn't currently match up to the config file alternative, and doesn't allow the other clients to connect.

2nd/3rd servers are stated as being

nats-server -p 5222 -cluster nats://localhost:5248 -routes nats://localhost:4248 -D
nats-server -p 6222 -cluster nats://localhost:6248 -routes nats://localhost:4248 -D

which start to work once the first servers port is changed to use 4248