Update Brax version to 0.14.2.

Increments the version number in `__init__.py`, `pyproject.toml`, and `README.md`, and renames the release notes file.

PiperOrigin-RevId: 884102953
Change-Id: I0be0a3c2c45e883523257d1b5d9133e5a155a161

Author: Brax Team

README.md

@@ -103,7 +103,7 @@ If you would like to reference Brax in a publication, please use:
   author = {C. Daniel Freeman and Erik Frey and Anton Raichuk and Sertan Girgin and Igor Mordatch and Olivier Bachem},
   title = {Brax - A Differentiable Physics Engine for Large Scale Rigid Body Simulation},
   url = {http://github.com/google/brax},
-  version = {0.14.1},
+  version = {0.14.2},
   year = {2021},
 }
 ```

brax/__init__.py

@@ -14,7 +14,7 @@
 
 """Import top-level classes and functions here for encapsulation/clarity."""
 
-__version__ = '0.14.1'
+__version__ = '0.14.2'
 
 from brax.base import Motion
 from brax.base import State

docs/release-notes/v0.14.2.md

@@ -0,0 +1,6 @@
+# Brax v0.14.2 Release Notes
+
+* **Distributional PPO Support**: Added a distributional critic to capture return
+variance, leading to more reliable advantage estimates and improved policy
+updates (reference: https://arxiv.org/abs/1710.10044).
+* Parametrize CNN networks in brax PPO.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "brax"
-version = "0.14.1"
+version = "0.14.2"
 description = "A differentiable physics engine written in JAX."
 authors = [
     { name = "Brax Authors", email = "no-reply@google.com" },