updated changelog

CHANGELOG.md

@@ -6,6 +6,19 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 
+## [v1.2.9] - 2025-08-05
+
+### Docs
+
+- Average document length now uses tokens instead of characters
+- Changes to `*/descriptive_stats.json`: 
+  - Object no longer includes revision. 
+  - Now include character-level metrics along with minimum and maximum length. Removed average document length as it is computable from existing metrics.
+- Removed per dataset histograms from main readme. The goal is to avoid loading in the entire dataset when updating the readme. This should make it easier to contributors.
+
+### CI
+- Fixes bug causing `make update-descriptive-stats` to fails when not having a linear commit history. The script now no longer skips a dataset update based revision, but simply based on whether the `descriptive_stats.json` exists. To ensure that the main readme is always up to date we change the make command to always update it.
+
 ## [v1.2.8] - 2025-08-05
 
 ### Added