doc/effective_go: fix server example that shares var between goroutines Use it as a teaching example about how to solve this problem.
doc/effective_go: fix server example that shares var between goroutines
Use it as a teaching example about how to solve this problem.

Fixes issue 6501

R=golang-dev, adg, rsc
CC=golang-dev
https://codereview.appspot.com/14250043

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang