Improve the Tags and Releases documentation (OKR)

What does this MR do?

Clean up and update the Releases and Tags documentation.

To tackle this iteratively, this MR tidies up style guide problems and updates some screenshots.

UX Recommendations: gitlab-design#505 (closed)
TW OKR Issue: #31711 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

N/A, docs only

Security

N/A, docs only