update the github actions workflow demo in github-pages.md

[ericclose]

Check List

Please read and check followings before submitting a PR.

• [ ] I want to publish my theme on Hexo official website.
  • [ ] I have read the theme publishing doc.
  • [ ] name is unique.
  • [ ] link URL is correct.
  • [ ] preview URL is correct.
  • [ ] preview URL web site is rendered correctly.
  • [ ] Add a screenshot to source/themes/screenshots.
  • [ ] Screenshot filename is same as value of name.
  • [ ] Screenshot size is 800 * 500.
  • [ ] Screenshot file format is png.
• [ ] I want to publish my plugin on Hexo official website.
  • [ ] I have read the plugin publishing doc.
  • [ ] name is unique.
  • [ ] link URL is correct.
• [ ] Others (Update, fix, translation, etc...)
  • Languages:
  • [x] en English
  • [ ] ru Russian
  • [x] zh-cn simplified Chinese
  • [x] zh-tw traditional Chinese

Note

No need to translate ko, pt-br, th languages if you submit a PR for documentation.

Warning

ko, pt-br, th languages document are inactive. Please, submit issue if you want to continuous contribution to them.

As I am unfamiliar with the utilization of Git, I apologize for the re-openning this pull request.

[github-actions[bot]]

Theme name validation passed. Theme thumbnails validation completed.