Documentation pages on GitHub Pages?

[tkokada]

Is your feature request related to a problem? Please describe.

• We don't update the sphinx documents.
• Only administrator can check the readthedocs management web site.

Describe the solution you'd like

• Add a new github action file to build the sphinx documentation and upload to GitHub Pages.

Describe alternatives you've considered

• Keep on the readthedocs, but everyone should update the docs when update the codes.
• We need additional payments for GitHub Pages, but not expensive.

[yoshipon]

Thank you for opening this issue! I think you have kindly and successfully updated the repository to use GH Pages.
Could you also update link URLs in the README*.md?