The document supports en and ja.

[tkokada]

The PR contains followings:

• Update the api reference and locale files (this update replace sooo many files in docs/source/api_reference and docs/source/locale directories).
• Support english and japanese on github pages.
• Add naive html to redirect to japanese page.
• Add naive html to add a button to select languages.

As mentioned above, htmls should be modified in future.
But the PR can support english and japanese by the button.
Most of the api reference generation are automated, but the localization process is sitll needed to modify by hands.
For example, if you update the docstring, followings are the instructions to update the api reference:

path/to/aiaccel/repo

$ sphinx-apidoc -f -o docs/source/api_reference aiaccel

$ cd docs

$ make gettext

$ sphinx-intl update -p build/gettext -l en -l ja

This generates localization files in docs/source/locale directory.
The instruction commands update (delete) the files if docs/source/locale includes translated files.

[yoshipon]

ありがとうございます！