Add README badges.

PiperOrigin-RevId: 717106946
Change-Id: I346aee1cc88f2271ff66fa4ace0e1d4c4154a3c0

Author: kevinzakka

README.md

@@ -1,8 +1,9 @@
 # MuJoCo Playground
 
+[![Build](https://img.shields.io/github/actions/workflow/status/google-deepmind/mujoco_playground/ci.yml?branch=main)](https://github.com/google-deepmind/mujoco_playground/actions)
+[![PyPI version](https://img.shields.io/pypi/v/playground)](https://pypi.org/project/playground/)
 ![Banner for playground](https://github.com/google-deepmind/mujoco_playground/blob/main/assets/banner.png?raw=true)
 
-
 A comprehensive suite of GPU-accelerated environments for robot learning research and sim-to-real, built with [MuJoCo MJX](https://github.com/google-deepmind/mujoco/tree/main/mjx).
 
 Features include: