Add changelog automation feature

[ofranc]

Add the ability to tag specific lines, blocks, or pages in GitBook and automatically aggregate those tagged items into a central, public changelog.

Problem: today, GitBook does not provide a way to:

• Mark (“tag”) specific changes inside documentation pages, and
• Automatically collect those marked changes into a structured changelog.

Proposed Solution ===> Introduce a Changelog Tagging System with the following capabilities:

1. Tagging

Allow users to tag:
A specific line or text selection
A block (paragraph, list, code block)
An entire page

Example tags:
changelog
release:1.4
breaking-change
feature
fix

2. Aggregation

Provide a dynamic Changelog page that:
Automatically aggregates all tagged content
Groups entries by release/version, date, or tag
Shows references back to the original page and location

3. Public Sharing

Changelog pages should be fully publicly shareable
Support filtering (e.g., show only breaking changes or a specific release)
Optional RSS/email notifications for new tagged entries