Japanese README and documents are now available! (v0.66.0)

[simon-ritchie]

Japanese README and all documents are now available!

You can access its README by the language links as follows:

Also, the all of the Japanese documents are available:

https://simon-ritchie.github.io/apysc/jp/jp_index.html

Notes: I've changed the documents' URLs to insert a language directory.

Before URL example: https://simon-ritchie.github.io/apysc/index.html
After URL example: https://simon-ritchie.github.io/apysc/en/index.html