docs: rewrite and unify documentation across all supported languages

- Rewrite and reorganize documentation for clarity and readability, including reworded introductions and consistent headings.
- Improve input parameter tables: clarify descriptions, unify formatting, and better explain parameter purposes across all three languages.
- Expand and update step-by-step SSH key setup guides, streamline copy instructions, and add practical notes and tips.
- Enhance usage examples with clearer titles, better labels, and updated YAML examples for different authentication methods and scenarios.
- Add new sections and tips on OpenSSH compatibility and troubleshooting "command not found" issues, with improved cross-platform guidance.
- Refine explanations for host fingerprint verification, proxy setup, and command environment management.
- Update and polish contributing and license sections for greater encouragement and style consistency.
- Apply the above documentation improvements to both Simplified and Traditional Chinese versions for parity.

Signed-off-by: appleboy <[email protected]>

Author: appleboy