docs: clarify yarn classic v1.x is required for contributing

[0xMayurrr]

Fixes #739

The README's Contributing section did not mention that
Yarn Classic (v1.x) is required. Contributors using
Yarn v2/v3 (Berry) run into setup issues. Added a
prerequisites note to clarify this.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 6940790e-cc4e-4a1c-8152-05597aaebe62

📥 Commits

Reviewing files that changed from the base of the PR and between 5eec825 and a477e00.

📒 Files selected for processing (1)

• README.md

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Walkthrough

This pull request adds a prerequisites section under the Contributing documentation to explicitly state that Node.js and Yarn Classic (v1.x) are required, with installation instructions. The addition addresses confusion around yarn version requirements for running project scripts.

Changes

Cohort / File(s)	Summary
Documentation README.md	Added prerequisites note under Contributing section documenting required Node.js and Yarn Classic (v1.x) versions with global yarn install command.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding documentation to clarify that Yarn Classic v1.x is required for contributing, which directly aligns with the PR's objective.
Description check	✅ Passed	The description clearly explains the change (adding prerequisites note), references the linked issue #739, and provides context about the problem Yarn v2/v3 users face.
Linked Issues check	✅ Passed	The PR successfully addresses issue #739 by adding documentation to the README's Contributing section clarifying Yarn Classic v1.x requirement, directly fulfilling the issue's objective.
Out of Scope Changes check	✅ Passed	The changes are limited to adding a prerequisites note in the README's Contributing section, staying within scope of the linked issue #739 which requests documentation of Yarn Classic requirement.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[0xMayurrr]

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[0xMayurrr]

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