[jaeger-v2] Document changes to admin port / services

* metrics are on a different port `address: 0.0.0.0:8888` (`address: 0.0.0.0:8889` for ingester)
* expvar is also on a different port via `expvar` extension: `port: 27777`
* Healthchecks are on a different port via `healthcheckv2` extension: `endpoint: "0.0.0.0:13133"`
