Minor edit to CONTRIBUTING.md for GSoC practice

[BHAVYABHEEMAVARAPU]

Hello! 👋
I'm applying for GSoC 2025 and made this small edit as a warm-up contribution.
I added a friendly message at the end of the contributing guidelines. Thank you for the opportunity! ✨

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📚 Documentation preview 📚: https://arviz--2446.org.readthedocs.build/en/2446/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.75%. Comparing base (ef7042b) to head (c41a72e).
Report is 12 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2446   +/-   ##
=======================================
  Coverage   86.75%   86.75%           
=======================================
  Files         124      124           
  Lines       12941    12941           
=======================================
  Hits        11227    11227           
  Misses       1714     1714           

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[BHAVYABHEEMAVARAPU]

Hi! I noticed that one of the checks (Azure Pipelines - Update with nightlies) has failed, but it seems unrelated to my changes. All core tests passed successfully, and the failure appears to be due to a missing nightly h5py package. Please let me know if anything else is needed from my side. Thanks!

[aloctavodia]

Thanks!