[BUG] Minigrid is not supported as per documentation

[AsadJeewa]

Describe the bug

When I create an envpool object I get the error:
AssertionError: MiniGrid-Empty-5x5-v0 is not supported, envpool.list_all_envs() may help.
The documentation states that it is meant to be supported here: https://envpool.readthedocs.io/en/stable/env/minigrid.html

To Reproduce

    envs = envpool.make(
        "MiniGrid-Empty-5x5-v0",
        env_type="gymnasium",
        num_envs=2,
    )

Expected behavior

Minigrid env should be created as per other supported environments

System info

Describe the characteristics of your environment:
Ubuntu 22.04, Python 3.10.12

Checklist

• I have checked that there is no similar issue in the repo (required)
• I have read the documentation (required)
• I have provided a minimal working example to reproduce the bug (required)