Fix broken link in zipkin-server/README.md
Fix broken link in zipkin-server/README.md
openzipkin/zipkin,abesto/zipkin,openzipkin/zipkin,adriancole/zipkin,adriancole/zipkin,twitter/zipkin,openzipkin/zipkin,abesto/zipkin,twitter/zipkin,openzipkin/zipkin,twitter/zipkin,abesto/zipkin,twitter/zipkin,openzipkin/zipkin,adriancole/zipkin,abesto/zipkin,adriancole/zipkin