docs: v3.0.1 changelog

Author: kozistr

docs/changelogs/v3.0.1.md

@@ -8,6 +8,8 @@
   * support not-using-first-momentum when beta1 is not given
   * default dtype for first momentum to `bfloat16`
   * clip second momentum to 0.999
+* Implement `GrokFast` optimizer. (#244, #245)
+  * [Accelerated Grokking by Amplifying Slow Gradients](https://arxiv.org/abs/2405.20233)
 
 ### Bug