Switch branch to main from master

[hiroyuki-sato]

It is a good idea to switch the branch to main.

#15 (comment)

• Switch branch main to master (master will be read-only branch)
• Change GitHub Pages publish branch
• Publish document using GitHub Actions? (Copy from https://github.com/embulk/embulk.github.io/blob/main/.github/workflows/publish.yml) with some modifications (actions/jekyll-build-pages@v1 part)
• And others?

[hiroyuki-sato]

@dmikurube May I change the default branch? Or Would you be able to do it later?
I can handle the first two steps.

[dmikurube]

@hiroyuki-sato Yeah, thanks! Please go ahead with the changes.

But note that "Publish document using GitHub Actions" may not work just by "copying as-is". The directory structure is a bit different here, and Jekyll is not so much used here.

[hiroyuki-sato]

@dmikurube Thanks! I've done the first two steps.

• created the main branch.
• change the master branch to read-only.
• GitHub Page build from main branch.

Publish documents using GitHub Actions will apply later. I need to test for that.