Update changelog

CHANGELOG.md

@@ -9,8 +9,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [UNRELEASED]
 
+### Breaking changes
+
+* The `token_usage()` and `tokens_reset()` functions have been removed. Use the new `.token_usage()` method on the `Chat` instance instead. (#23)
+* The `.tokens()` method on the `Chat` instance was removed because you usually only care about `.token_usage()`. If you do indeed want the input/output tokens for each turn, you can `.get_turns()` on the chat instance, and then get the `.tokens` of each turn. (#23)
+
 ### New features
 
+* The `Chat` class gains a `.token_count()` method to help estimate input tokens before sending it to the LLM. (#23)
+
 ### Bug fixes
 
 * `ChatOllama` no longer fails when a `OPENAI_API_KEY` environment variable is not set.