Given a mention in release notes

Author: Sayam753

Diff for: RELEASE-NOTES.md

@@ -45,6 +45,7 @@ This new version of `Theano-PyMC` comes with an experimental JAX backend which,
 - Enabled the `Multinomial` distribution to handle batch sizes that have more than 2 dimensions. [#4169](https://github.com/pymc-devs/pymc3/pull/4169)
 - Test model logp before starting any MCMC chains (see [#4116](https://github.com/pymc-devs/pymc3/issues/4116))
 - Fix bug in `model.check_test_point` that caused the `test_point` argument to be ignored. (see [PR #4211](https://github.com/pymc-devs/pymc3/pull/4211#issuecomment-727142721))
+- Refactored MvNormal.random method with better handling of sample, batch and event shapes. [#4207](https://github.com/pymc-devs/pymc3/pull/4207)
 
 ### Documentation
 - Added a new notebook demonstrating how to incorporate sampling from a conjugate Dirichlet-multinomial posterior density in conjunction with other step methods (see [#4199](https://github.com/pymc-devs/pymc3/pull/4199)).