Add environments demo video to homepage (#954)

docs/index.md

@@ -57,12 +57,14 @@ Contribute to the Docs <https://github.com/Farama-Foundation/PettingZoo/tree/mas
 
 ```
 
-# PettingZoo is a standard API for multi-agent reinforcement learning
+# PettingZoo is a standard API for multi-agent reinforcement learning.
 
-```{figure} environments/atari/atari_warlords.gif
-    :width: 230px
-    :name: warlods
-```
+
+<center>
+	<a href="_static/videos/environments-demo.mp4">
+        <video title="PettingZoo environments" autoplay loop muted width="450" src="_static/videos/environments-demo.mp4" type="video/mp4"></video>
+    </a>
+</center>
 
 **PettingZoo includes a diverse set of reference environments, and a simple, pythonic interface capable of representing general multi-agent reinforcement learning (MARL) problems.**