Default concurrency is NumCPU, not 4

[ryboe]

I was confused by this section of the --help text. I wondered why concurrency was defaulting to 4, instead of using runtime.NumCPU() to scale the number of workers to the user's actual number of cores.

Flags:
  -j, --concurrency int           Concurrency (default 4)

Apparently, you are doing this 😀👍

rootCmd.PersistentFlags().IntVarP(&e.cfg.Run.Concurrency, "concurrency", "j", runtime.NumCPU(), "Concurrency")

https://github.com/golangci/golangci-lint/blob/master/pkg/commands/root.go#L64

I think the --help text should be updated to Concurrency (default NumCPU) or similar. Go programmers will recognize NumCPU as runtime.NumCPU().

@y0ssar1an thank you!
fixed in #27