License confirmation

[TC01]

I'm looking into packaging this project in Fedora. A question emerged in the review about licensing and I was hoping to get clarification.

Specifically, as there are not license headers on individual Go code files (e.g. in cmd/markdown), can you confirm that this project and all of its contents under the same license(s) as peg-markdown (i.e. GPLv2+ or MIT)? It would be great if you could add license headers to all the source files too.