Add "Syncing Forked Repository" Instructions to CONTRIBUTING.md

[anshiagrawal22]

Hello Mentors and Admins,

I’m a GSSoC'25 contributor. I’d like to suggest adding a section in the CONTRIBUTING.md file that explains how to sync a forked repository with the main project repo. This is a common step contributors need to perform, and including it would help newcomers keep their forks up-to-date with the main project and avoid conflicts.

I’d be happy to create a PR for this if approved. Let me know your thoughts!