Q: How to contribute Japanese translation of Codelabs Tutorial?

Thanks for [the wonderful codelabs tutorial](https://codelabs.developers.google.com/codelabs/firestore-web/)!

My friends @isamu, @Mikkegt, others and I made a Japanese translation of the codelabs tutorial and are willing to contribute it back to the community. As we don't see the tutorial text in this github repo, we're wondering what is the best way for us to contribute it... (if there were the English version in this repo, we'll submit a PR with the Japanese version put in parallel...)

Here is the Japanese version in a github repo: https://github.com/isamu/friendlyeats-web-docs/blob/master/TUTORIAL.md

And this is its codelabs version: https://isamu.github.io/friendlyeats-web-docs/dist/#0

Could you please give us some suggestions?
Thank you in advance!