Given a mention in release notes

Author: Sayam753

Diff for: RELEASE-NOTES.md

@@ -14,6 +14,7 @@ This is the first release to support Python3.9 and to drop Python3.6.
 - In `sample_posterior_predictive` the `vars` kwarg was removed in favor of `var_names` (see [#4343](https://github.com/pymc-devs/pymc3/pull/4343)).
 - The notebook gallery has been moved to https://github.com/pymc-devs/pymc-examples (see [#4348](https://github.com/pymc-devs/pymc3/pull/4348)).
 - `math.logsumexp` now matches `scipy.special.logsumexp` when arrays contain infinite values (see [#4360](https://github.com/pymc-devs/pymc3/pull/4360)).
+- Fixed mathematical formulation in `MvStudentT` random method. (see [#4359](https://github.com/pymc-devs/pymc3/pull/4359))
 
 ## PyMC3 3.10.0 (7 December 2020)