Add docstring to MujocoEnv.__init__() (#522)

gymnasium/envs/mujoco/mujoco_env.py

@@ -40,6 +40,22 @@ def __init__(
         camera_id: Optional[int] = None,
         camera_name: Optional[str] = None,
     ):
+        """Base abstract class for mujoco based environments.
+
+        Args:
+            model_path: Path to the MuJoCo Model.
+            frame_skip: Number of mujoco simulation steps per gym `step()`.
+            observation_space: The observation space of the environment.
+            render_mode: The `render_mode` used.
+            width: The width of the render window.
+            height: The height of the render window.
+            camera_id: The Default camera used.
+            camera_name: The name for the default camera.
+
+        Raises:
+            OSError: when the `model_path` does not exist.
+            error.DependencyNotInstalled: When `mujoco` is not installed.
+        """
         if model_path.startswith("/"):
             self.fullpath = model_path
         else: