Improve version input documentation in README

[Copilot]

The version input lacked clear documentation on its purpose and usage, particularly regarding semver range support.

Changes

• Added dedicated "Version Input" section explaining:

  • Controls which Swagger UI version is used for generation
  • Accepts semver ranges (5.x, ^3.0.0, 5.0.0)
  • Defaults to ^3.0.0
  • Links to npm semver range documentation

• Updated example workflow to demonstrate version pinning:

- name: Generate Swagger UI
  uses: Legion2/swagger-ui-action@v1
  with:
    output: swagger-ui
    spec-file: openapi.json
    version: 5.x
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

• Applied prettier formatting for consistency

Original prompt

Improve the documentation of the 'version' input in the README. Specifically:

• Add a brief section that explains what the 'version' input does, and mention that it accepts semver ranges.
• Update the example YAML usage in the README to include the 'version' input, e.g.:
  version: 5.x
• Make sure the new documentation is clear, concise, and follows the structure and style of the rest of the README.

This pull request was created from Copilot chat.

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