docs: v3.0.1 changelog

Author: kozistr

docs/changelogs/v3.0.1.md

@@ -4,6 +4,10 @@
 
 * Implement `FAdam` optimizer. (#241, #242)
   * [Adam is a natural gradient optimizer using diagonal empirical Fisher information](https://arxiv.org/abs/2405.12807)
+* Tweak `AdaFactor` optimizer. (#236, #243)
+  * support not-using-first-momentum when beta1 is not given
+  * default dtype for first momentum to `bfloat16`
+  * clip second momentum to 0.999
 
 ### Bug