docs: add commit signing summary

[Uiyrte]

Pull Request Template

Goal

Configure secure commit signing using SSH keys to ensure author authentication and Git history integrity.

Changes

• Generated SSH key using ssh-keygen
• Public key added to GitHub as a Signing Key
• Git configured to use SSH signing (gpg.format ssh)
• Automatic commit signing enabled (commit.gpgsign true)

Testing

• Commits are performed with the -S flag and checked for the presence of the Verified label in the GitHub interface
• Checked that commits are signed automatically without errors

Checklist

• PR has a clear, descriptive title
• Documentation / README updated if needed
• No secrets or large temporary files included
• Task 1 done
• Task 2 done
• Screenshots attached (if applicable)