GOMAXPROCS will be set automatically after Go 1.5. The minimum version supported at the moment is 1.9, so setting GOMAXPROCS to NumCPU is not necessary anymore. References https://docs.google.com/document/d/1At2Ls5_fhJQ59kDK2DFVhFu3g5mATSXqqV5QrxinasI/edit https://tip.golang.org/doc/go1.5#introduction
According to install.md, the minimum version of Go supported at the moment is 1.9, so update the Go version referenced in Contribution Checklist to 1.9 as well.