Create How-to-contribute[English].md

[upura]

I suppose that it would be desirable to creat How-to-contribute[English].md in Wiki for non-Japanese contributors. The following is the English translation of How to contribute.md, and there is no permission for me to edit Wiki.

Best,

# How to contribute

Contributors, thank you for participating in this project!

I'm Seki, the development manager. If you have any questions, feel free to ask me on Slack etc.

This page shows how you can contribute to the development of this site.

## Comments on Issues and Pull Requests
* Feel free to comment on the Issue! Questions and suggestions are also welcome.
* You can fix some issues via Pull Request.

## How to participate in communications
* If you do not have a Slack account of "Code for Japan", please register [here](https://cfjslackin.herokuapp.com/)
* Join `#covid19` Channel

## For participation
* Please read [Principle / Code of Conduct](Principle%5BEnglish%5D) before participating in developments.
* For communications, please also check Code of Japan's [Code of Conduct](https://github.com/codeforjapan/codeofconduct).
* If you find some issues that you can do, please assign yourself!
* [good first issue label](https://github.com/tokyo-metropolitan-gov/covid19/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) is recommended for beginners
* If you can't have any progress for more than half a day, make sure that others can take over your work.
* In case issues are not updated for more than one day, we may remove the assign. [Draft Pull Request](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-requests#draft-pull-requests) is recommended so that everyone knows the situation.
* For any questions related to the Issue, we should discuss in the Issue comments than Slack.
* We also accept suggestions! Please fell free to create new issues.

## Development information
* Development site https://dev-covid19-tokyo.netlify.com/
* Staging site https://stg-covid19-tokyo.netlify.com/
* Production site https://covid19-tokyo.netlify.com/
* [Design](https://www.figma.com/file/V7vt80p2gauhdgTZeVNbgj/UI%E3%83%87%E3%82%B6%E3%82%A4%E3%83%B3?node-id=121%3A156)

Updates to this Wiki are also welcome!

[halsk]

Thank you so much for your great contribution!!! However, I have revised the original text a few minutes ago. Could you please update your text as well?

https://github.com/tokyo-metropolitan-gov/covid19/wiki/How-to-contribute

[upura]

Thank you. The text has been updated based on the diff of the original text. Please feel free to edit & use it.

Once English version has been published, it would be better to update the link in README.md. I'll send a PR if I need.

All contributions are welcome! Please check How to contribute for details.

[halsk]

@upura I created the English how to contribute page! Thank you for your contribution! https://github.com/tokyo-metropolitan-gov/covid19/wiki/How-to-contribute%5BEnglish%5D