Changelog: Deprecation notice for Notebooks feature

[jdorfman]

Before you merge this PR, please review the following:

Blog post

• Checked title case (This is correct. This Is Not Correct)
• Updated publishDate
• Updated authors
• Updated and checked slug
• Proofread for spelling and grammar errors
• Checked for consistent tone and voice throughout via Grammarly
• Ensured all links are working correctly
• Added relevant tags and categories
• Optimized meta description
• Included a new hero and social/OG image
• Uploaded images to Google Storage
• Formatted text for readability (headings, bullet points, etc.)
• Added image alt text
• Ran Markdown linter

Other

• This is not a blog post

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