[FEATURE]: Add a Signature

[Rudra-G-23]

🔑 Short Summary / Problem Statement

Add a Signature when file is created. For marketing this library ... 😁

💡 Proposed Solution / Feature Description

• A few lines of code during the file generated at the end or at the top.
• Try both styles and implement what is suitable

🎯 Use Case / Motivation

• Marketing our package. 😁

🔄 Alternatives Considered (if any)

No response

📎 Additional Context / References

Example:

This file is created through the show-file-tree

⚠️ Priority / Importance

None

🧩 Affected Modules / Components

• CLI (cli.py)
• Tree Builder (tree_builder.py)
• Tree Renderer (tree_renderer.py)
• Markdown Export (md_exporter.py)
• Notes Manager (notes_manager.py)
• New module
• Other

🔗 Dependencies / Requirements

No response

✅ Pre-Submission Checklist

• Problem clearly described
• Proposed solution explained
• Use case/motivation provided
• Checked for similar existing features
• Included references or mockups (if applicable)