improve documentions

[shadil-rayyan]

Description

We would like to improve and expand the technical documentation of the rss_cse_picker project.
Currently, the README covers basic usage, but we want a more complete guide for both end-users and developers/contributors.

The goal is to make it clear, professional, and easy to maintain, including:

• Detailed project overview
• Clear user instructions (how to download OPML, import feeds)
• Clear contributor workflow (adding feeds in Excel, running conversion script, generating JSON/OPML, submitting PRs)
• Explanation of file structure and scripts (feeds.xlsx, convertExcelToJson.js, etc.)
• Optional FAQ / troubleshooting section for common issues
• Guidelines for adding new categories or feeds
• Examples of Excel entries → JSON → OPML
• Proper license and attribution info

Tasks

• Review and improve the README.md
• Add a separate CONTRIBUTING.docx or guide for developers
• Include examples and screenshots if necessary
• Ensure instructions are easy for non-developers to follow
• Add notes about workflow for maintaining feeds

Expected Outcome

• A polished, professional, and comprehensive technical documentation set
• Easier onboarding for contributors and end-users
• Reduced errors or confusion when adding new feeds

Notes

• This is primarily a documentation improvement task — no code changes required unless scripts need clarification.
• Contributions can include text, diagrams, or example files.

[nayna-G]

@shadil-rayyan i have sent a PR. check