Cobra OpenCLI #73

Hi,

I've created a lib to convert Cobra commands to OpenCLI format. It's a Go library you can use in your Golang codebases. As output it's an OpenCLi Specification in Go types or raw yaml bytes.

I've also added a PR to Cobra as an experimental docs output format, but I'm not quite sure if it will be acceptable to maintainers. Nevertheless, a standalone lib is fixing that.

Best,