testing: document test.bench flag in the testing pkg's docs #4080
Description
What steps will reproduce the problem? 1. Go to http://golang.org/pkg/testing 2. Try to find what to type in test.bench, or what type the flag is What is the expected output? What do you see instead? Something like what we can find in the testing/benchmark.go code: - regular expression to select benchmarks to run Please use labels and text to provide additional information.