docs: apply feedback (github label and scrollbarstate change)

BREAKING-CHANGES.md

@@ -1,10 +1,20 @@
 # Breaking Changes
 
 This document contains a list of breaking changes in each version and some notes to help migrate
-between versions.
+between versions. It is compile manually from the commit history and changelog. We also tag PRs on
+github with a [breaking change] label.
+
+[breaking change]: (https://github.com/ratatui-org/ratatui/issues?q=label%3A%22breaking+change%22)
 
 ## Unreleased (0.24.0)
 
+### ScrollbarState field type changed from `u16` to `usize` ([#456])
+
+[#456]: https://github.com/ratatui-org/ratatui/pull/456
+
+In order to support larger content lengths, the `position`, `content_length` and
+`viewport_content_length` methods on `ScrollbarState` now take `usize` instead of `u16`
+
 ### `BorderType::line_symbols` renamed to `border_symbols` ([#529])
 
 [#529]: https://github.com/ratatui-org/ratatui/issues/529