docs: clarify Copilot quick start command

[shivangiii18]

Summary

• Update the Quick Start section to use the correct initialization commands.
• Separate the commands for Claude Code and Copilot to avoid confusion.

Closes #

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[tapheret2]

Review: docs: clarify Copilot quick start command

Files: README.md
Size: +2 / -1

Notes

• Static pass on the patch: no obvious blockers from the diff alone.

Thanks @shivangiii18 — independent review on the patch.