Document advanced Git workflows with practical examples

[Copilot]

Adds concise documentation for advanced Git commands with examples to help users apply git stash, git cherry-pick, git revert, and git reset correctly.

• Documentation updates
  • Added an “Advanced Git Commands” section in README detailing usage patterns and caveats for each command.
  • Included practical command examples for common workflows.

Example snippet:

# Save local work without committing
git stash push -m "wip: feature-x"

# Apply a specific commit from another branch
git cherry-pick <commit-sha>

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