Add a README for ja

[bmf-san]

Description

Nice to meet you. I'm a Japanese software engineer who finds air very useful for go development. :)

I've added a Japanese README.

It seems that air is also often used in go development in Japan.

I am not a native speaker of English, but I am a native speaker of Japanese.
I have been careful not to change the meaning of the original text, and have tried to avoid free translation as much as possible.

Changes

• Added README-ja.md
• Added a link to README-ja.md to README.md

Supplement

When translating, I kept the following points in mind:

• Use polite language
• Do not add punctuation at the end of sentences in bullet points
• Do not translate expressions that are likely to be understood in their original English
  • This applies to "Pull Request" and "Issue"
    • I thought that Japanese developers using Github would not need a Japanese translation

Issue

N/A

[xiantang]

well done, let me review that.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[bmf-san]

@xiantang
How's the review for my recent commit coming along? 👀

[xiantang]

@xiantang How's the review for my recent commit coming along? 👀

日本語は苦手です🥹

[xiantang]

i will continue take a look this PR

[xiantang]

i translate back to my language, looks good to me totally

[xiantang]

could u add a space between English and Japanese?
for example:
this is the Chinese version

[bmf-san]

@xiantang
Thanks for your review :D
Understood, I've done!