Missing Complete English Documentation

[bagustris]

Is your feature request related to a problem? Please describe. This issue related to #55.

The English version documentation pointed to the same Japanese documentation. https://aiaccel.readthedocs.io/en/latest/index.html

Describe the solution you'd like Provide the correct English translation in English section of documentation.

Describe alternatives you've considered This request may not be implemented since the major user of ABCI are Japanese, but if it is implemented, it will increase users of aiaccel, particularly outside the use in ABCI.

Additional context Having aiaccel instead of vanilla optuna may increase the users of aiaccel. I'll try to start to translate the PO files from Japanese to English if this proposal is accepted .