Update changelog

Author: cpsievert

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `shiny create` includes new and improved `ui.Chat()` template options. Most of these templates leverage the new [`{chatlas}` package](https://posit-dev.github.io/chatlas/), our opinionated approach to interfacing with various LLM. (#1806)
 
+* Client data values (e.g., url info, output sizes/styles, etc.) can now be accessed in the server-side Python code via `session.clientdata`, which is collection of reactive `Inputs`. For example, `session.clientdata.url_search()` reactively reads the URL search parameters. See [this PR](https://github.com/posit-dev/py-shiny/pull/1832) for a more complete example. (#1832)
+
 ### Bug fixes
 
 * `ui.Chat()` now correctly handles new `ollama.chat()` return value introduced in `ollama` v0.4. (#1787)