Add Japanese README

[eltociear]

I created Japanese translated README.

[eltociear]

Do docs/hacking.md and docs/installation.md also need to be translated?

[VitoVan]

Thank you, Ashimine-san!

Do docs/hacking.md and docs/installation.md also need to be translated?

It's all up to you!

BTW the README.md has changed a few since the last update, you could check it here:

1.1.0...1.1.1#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5

Take your time, and I hope you enjoy.

[eltociear]

Understood!
I will translate docs/hacking.md and docs/installation.md another time!

Sorry, I missed that update. I will update the README!

[VitoVan]

Understood! I will translate docs/hacking.md and docs/installation.md another time!

Sorry, I missed that update. I will update the README!

No problem! Now the Japanese web page is ready:

https://vitovan.com/calm/index_ja.html

The original font-family in the CSS didn't take care of Japanese characters, so fire up another issue or PR if you have any better choice!