What kind of change does this PR introduce?

Issue Number:

• Closes [📝 Docs]: Enhance the Contribution Docs Guide for Better Readability and Structure json-schema-org/website#1124

If relevant, did you update the documentation?

I updated the documentation by adding a table of content and formatting it to make it easier for beginners to understand and navigate

Summary

I added a table of contents to the contributing guide which was not there previously and not mentioned in the issue I created for this.