docs: add data source section

[MoustafaAMahmoud]

Motivation and Context

Enhance the data source section documentation

Description

Contribution Checklist

• [ ] I have built and tested the code locally and in a deployed app
• [ ] For frontend changes, I have pulled the latest code from main, built the frontend, and committed all static files.
• [ ] This is a change for all users of this app. No code or asset is specific to my use case or my organization.
• [ ] I didn't break any existing functionality :smile: