Clarifies zipkin-server's endpoints and how configuration works
Clarifies zipkin-server's endpoints and how configuration works

This highlights that zipkin-server is a Spring Boot application, as that
clarifies which admin endpoints are available. It also makes explicit
that environment variables are actually bound to yaml configuration.

abesto/zipkin,adriancole/zipkin,twitter/zipkin,twitter/zipkin,adriancole/zipkin,adriancole/zipkin,abesto/zipkin,abesto/zipkin,openzipkin/zipkin,adriancole/zipkin,openzipkin/zipkin,openzipkin/zipkin,abesto/zipkin,twitter/zipkin,twitter/zipkin,openzipkin/zipkin,openzipkin/zipkin