docs: v3.1.0 changelog

Author: kozistr

docs/changelogs/v3.1.0.md

@@ -13,9 +13,10 @@
 
 ### Refactor
 
-* Refactor `AdamMini`. (#258)
+* Refactor `AdamMini` optimizer. (#258)
 * Deprecate optional dependency, `bitsandbytes`. (#258)
 * Move `get_rms`, `approximate_sq_grad` functions to `BaseOptimizer` for reusability. (#258)
+* Refactor `shampoo_utils.py`. (#259)
 
 ### Bug