cmd/go-contrib-init: add start of new tool to help new Go contributors
cmd/go-contrib-init: add start of new tool to help new Go contributors

Updates golang/go#17802

Change-Id: Ieb4be41039d414a3ba6766d98ed95a6154f964f4
Reviewed-on: https://go-review.googlesource.com/45078
Reviewed-by: Steve Francia <97224216d9b4001d2da5fac1d1d534510be40bbe@golang.org>

golang/tools,golang/tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,golang/tools,golang/tools,syreclabs/go-tools,golang/tools,syreclabs/go-tools