Support document generation and updating in konfig ci pipeline

[amyXia1994]

Enhancement

• We need to provide a web page to display all the model docs (whether they are built-in konfig models or created by users) for the users of the models to quickly obtain an understanding of what these models provide and how to use them.

  • There needs to be a stable web page to display all the model docs
  • The docs need to be synced once the models were released(for example, merged into the main branch)

• We need to provide a reproducible method(maybe a github action template) for users to establish their own automatic document syncing system.

[amyXia1994]

A real world example: the newly added models in #43 need to trigger automatically doc updating to kusionstack.io which has not been adopted to konfig repo yet.

[amyXia1994]

• we can use GitHub Pages to display the docs, and here's the settings page of the Konfig repo: https://github.com/KusionStack/konfig/settings/pages. Now it's set up to show the content under the doc/ directory of the doc sync branch
• there are existing out-of-box GithubPage updater, for example: peaceiris/actions-gh-pages@v3.7.3, it can automatically publish the generated content in pipeline to certain branch.