Protobuf Port Typo on Building a Local Test Environment Page [JIRA: RCS-387]

https://docs.basho.com/riak/cs/2.1.1/tutorials/fast-track/local-testing-environment/#step-3-set-service-configurations-and-start-the-services

```
listener.protobuf.internal = 127.0.0.1:8097
```

There are two instances of this in the example and upon checking, the port used by the configuration items on Riak CS and Stanchion uses the default `8087` Protobuf port. 

