Docs: Refactor "How to Contribute" section for clarity and formatting (#399)

[adarsh-priydarshi-5646]

Description of Changes

This PR improves the readability and formatting of the "How to Contribute" section in DISCOVER/14_how_to_contribute.md.

Changes Made:

• Updated heading to # How to Contribute for clarity.
• Broke long sentences into shorter lines for better readability.
• Removed an unnecessary extra dash in the bullet list.
• Standardized the feedback section to match other bullets.

Related Issue

Closes #399

Type of Change

• [x] ✨ Content Enhancement—Updates or improves existing content

Additional Notes (Optional)

Tested locally by building the book and viewing the updated section in the browser. No functional changes, only documentation improvements.

Checklist

• [x] I have searched open pull requests to avoid duplicates.
• [x] I have built the book locally using the build instructions and verified my changes work as expected.
• [x] I have written clear, conventional commit messages, as per the Pull Request Guidelines.

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[adarsh-priydarshi-5646]

Hi maintainers,

I’ve updated the "How to Contribute" section to improve formatting and readability. This PR refactors headings and bullet points and removes minor inconsistencies.

Closes #399

I’d appreciate it if you could review this PR when convenient. Thank you! 🙏

[github-actions[bot]]

This pull request has been inactive for 30 days. It will be closed in 14 days if no further activity occurs.

[adarsh-priydarshi-5646]

@OriolAbril Please review.