content: update anvil ga notice (#4543)

[frano-m]

Ticket

Closes #4543.

Reviewers

@NoopDog.

This pull request updates the announcement content for the general availability of the AnVIL Data Explorer to improve clarity, structure, and user engagement. The changes include rewriting the text for a more engaging tone, reorganizing the content into thematic sections, and updating links and instructions for better usability.

Content improvements and restructuring:

• Rewrote the announcement to adopt a more engaging tone, replacing formal language with a more approachable style.
• Organized the content into thematic sections (Key Features, Seamless Integration, Getting Started, Expanding Dataset Collection, and We Value Your Input) for improved readability and emphasis on key points.

Usability enhancements:

• Updated links to ensure consistency and accessibility, including the user guide link and feedback submission instructions.
• Highlighted new features such as faceted searches, seamless integration with Terra, and flexible data export options to better communicate the platform's capabilities.

[Copilot]

Pull Request Overview

This pull request updates the announcement content for the general availability of the AnVIL Data Explorer to improve clarity, structure, and user engagement. The changes transform a formal announcement into a more engaging, well-organized communication.

• Restructured content into thematic sections for better readability
• Adopted a more engaging and approachable tone throughout
• Updated links and instructions for improved usability and consistency