Add a workflow to publish the docs with github actions

[sugatoray]

Material for MkDocs generated documentation can be created with a GitHub workflow. Adding this will ensure the documentation gets updated in-sync with the codebase.

Here's an example: https://sugatoray.github.io/TrustLLM/index.html

Go to settings of this repository, then choose Pages and then select gh-pages as the branch and /root as the location. Mkdocs will produce the website artifacts inside the gh-pages branch and not populalet the main branch with the artifacts in the site folder.