docs: fix writing docs contribution link in README

[itskitto]

Preface

Hi all! I went ahead and submitted this small documentation fix directly, but please let me know if you prefer issues to be opened first for future contributions.

Thanks!

Short Description

Updates the broken Writing Docs contribution link in the repository README.

Changes

• Corrects the link to the current Writing Docs guide.

Validation

• Confirmed the updated URL opens the correct documentation page.
• Reviewed the diff to ensure no unrelated changes were introduced.

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[taylordowns2000]

wonderful! thank you @itskitto !