Add devcontainer and using git action to deploy docs

[Truongphi20]

Hi @smcclatchy,

I'm a genomic researcher and really excited about your free QTL mapping course! I’ve added a few enhancements to make the course structure more portable and easier to develop further.

Updates

• Devcontainer setup
  Added a ready-to-use devcontainer with Docker. You can quickly start working in VSCode via Ctrl+Shift+P → Devcontainer: Reopen in Container.

• Folder cleanup
  Ignored auto-generated files to keep the repo tidy:

  • Markdown figures in ./fig
  • Temporary markdown files in _episodes

• GitHub Actions deployment

  • Workflow set up to deploy the docs, separating code from deployment. Codebase is maintained on branch main, and branch gh-page is used for deployment,
  • To deploy, go to GitHub GUI of repository: Actions → Deploy to GitHub Pages → Run workflow.

I already tested and deployed successfully. See :

• My trial repo: https://github.com/Truongphi20/mapping_qtl
• Trial deployment: https://truongphi20.github.io/mapping_qtl/