Improve deploy action

[daaa1k]

What

• The actions used for building mdbook and deploying to GitHub Pages have been changed from community-maintained ones to official ones. According to this comment Fix deploy error #4 (comment)
• GitHub URL has been changed to new one.

Why

This decision was made in consideration of deployment health and support systems in the future.

Remarks

I've already confirmed if this workflow succeed in my fork. Pages are already unpublished.
https://github.com/daaa1k/purescript-book/actions/runs/22166552920

Important

Some settings need to be changed. Please modify the settings according to the figure below before merging this PR.

1. Set GitHub Pages Source as GitHub Actions
   

2. Add ja as github-pages deployment branch
   

[daaa1k]

@gemmaro
Could you please check this?

By the way, I think the following steps are not necessary, because I assume that README.md is not used to build mdbook. How do you think? Should we remove these steps?
https://github.com/daaa1k/purescript-book/blob/e4f5f8efcb78e7f76eb88378dadc0651a0d1b8aa/.github/workflows/mdbook.yml#L34-L43

[gemmaro]

@daaa1k Thank you so much! I followed your instructions in the remarks section.

By the way, I think the following steps are not necessary, because I assume that README.md is not used to build mdbook. How do you think? Should we remove these steps?

Actually, I'd prefer to keep those steps in our translation. So let's leave them as they are for now.
README.md is used to build with mdBook, since the top Foreword page (ja: "序文") comes from that file.

I haven't noticed that the original has the Release section and that it has been missing in the translation. Good catch.

[daaa1k]

@gemmaro

I haven't noticed that the original has the Release section and that it has been missing in the translation. Good catch.

Understood. I've fixed it. #6