docs: fix contributor heading

[ayaanoncrypto]

Fix the typo in the contributor guide heading from Preperaing Changes to Preparing Changes.

Validation:

• git diff --check passed.

[vercel]

Someone is attempting to deploy a commit to the Uneven Labs Team on Vercel.

A member of the Team first needs to authorize it.

[greptile-apps]

Greptile Summary

Corrects the contributor-guide heading in README.md from “Preperaing Changes” to “Preparing Changes.” The updated heading was confirmed at line 18, and the README passed whitespace and formatting checks. No defects were found.

Confidence Score: 5/5

Safe to merge: the change is limited to a corrected README heading and preserves document formatting.

The committed change was compared with its parent, confirming the exact corrected heading and the absence of the prior misspelling. Whitespace and Prettier checks also completed successfully.

Files Needing Attention: None. README.md was checked and requires no further changes.

T-Rex Logs

What T-Rex did

• I ran the README heading validation script against the committed change and its parent revision, confirmed that line 18 changed from a misspelled heading to '#### Preparing Changes', and then executed git diff --check and pnpm exec prettier --check README.md, both of which completed successfully.
• I generated artifacts documenting the validation, including the README heading validation script and the successful validation output.
• I inspected the validation script source and its associated output log to verify the exact before/after heading, the involved IDs, and that the whitespace and formatting checks passed.

_{Ran code and verified through T-Rex}

_{Reviews (1): Last reviewed commit: "docs: fix contributor heading" | Re-trigger Greptile}