Add Japanese Version Contributor Docs

[RuimingShen]

Changes:

add japanese version of contributor docs, add ja directiory under translation directory and modified the index.js, dev.js file under translation directory.

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated
• This is a documentation PR.

[limzykenneth]

@RuimingShen We recently have some updates to the contributor docs (including removing/archiving some docs there), just want to check if this version is matching the updated version already or not yet? Thanks.

[RuimingShen]

@RuimingShen We recently have some updates to the contributor docs (including removing/archiving some docs there), just want to check if this version is matching the updated version already or not yet? Thanks.

@limzykenneth Hello, I checked all the newest document, and made change to files that were commited after 3.18. Files that don't change should not have problem since the latest change for these are 10 months ago.

[limzykenneth]

Looks good. Thanks!