✨ feat(ci): add GitHub Action entrypoint and CI docs tabs

[AliRezaTaleghani]

Add a Docker entrypoint script for the Versify GitHub Action and
enhance the CI/CD documentation with selectable integration methods.

Most important changes:

• Add entrypoint.sh that builds CLI args from ACTION inputs,
  executes /versify, determines whether a version bump occurred by
  comparing against a baseline or latest tag, and writes outputs.
  This enables the action container to run Versify and emit
  new_version and should_bump for downstream steps.
• Replace a single GitHub Actions example in docs/index.html with
  tabbed CI/CD instructions (GitHub Action and Manual Setup). The
  Action tab contains a complete example workflow using
  OpScaleHub/versify and softprops/action-gh-release.
• Simplify the inline action example step that runs versify in the
  docs (removed redundant comments) and improve guidance text.

Why:

• Provide a usable entrypoint so the action container can accept
  inputs, run Versify reliably, and set outputs for release robots.
• Make the documentation clearer and more flexible by offering both
  an easy GitHub Action integration and manual CI/CD instructions.