Update text description for tfds data action and observation.state

[youliangtan]

The text description in bridge_dataset/1.0.0/features.json is incorrect.

"action": {
    "pythonClassName": "tensorflow_datasets.core.features.tensor_feature.Tensor",
    "tensor": {
        "shape": {
            "dimensions": [
                "7"
            ]
        },
        "dtype": "float32",
        "encoding": "none"
    },
    "description": "Robot action, consists of [7x joint velocities, 2x gripper velocities, 1x terminate episode]."
},

"state": {
    "pythonClassName": "tensorflow_datasets.core.features.tensor_feature.Tensor",
    "tensor": {
        "shape": {
            "dimensions": [
                "7"
            ]
        },
        "dtype": "float32",
        "encoding": "none"
    },
    "description": "Robot state, consists of [7x robot joint angles, 2x gripper position, 1x door opening angle]."
},

Both should be in cartesian space reference to base_link. with state: [x, y, z, roll, pitch, yaw, gripperstate] and action: [dx, dy, dz, droll, dpitch, dyaw, gripperstate]