Update meta/modality.json

- Consolidate the motor states and actions to just two fields namely "single_arm" and "gripper" to be more semantically meaningful
- Add "annotation" field to enable language modality

meta/modality.json

@@ -1,54 +1,22 @@
 {
     "state": {
-        "motor_1": {
-            "start": 0,
-            "end": 1
+        "single_arm": {
+          "start": 0,
+          "end": 5
         },
-        "motor_2": {
-            "start": 1,
-            "end": 2
-        },
-        "motor_3": {
-            "start": 2,
-            "end": 3
-        },
-        "motor_4": {
-            "start": 3,
-            "end": 4
-        },
-        "motor_5": {
-            "start": 4,
-            "end": 5
-        },
-        "motor_6": {
-            "start": 5,
-            "end": 6
+        "gripper": {
+          "start": 5,
+          "end": 6
         }
     },
     "action": {
-        "motor_1": {
-            "start": 0,
-            "end": 1
-        },
-        "motor_2": {
-            "start": 1,
-            "end": 2
+        "single_arm": {
+          "start": 0,
+          "end": 5
         },
-        "motor_3": {
-            "start": 2,
-            "end": 3
-        },
-        "motor_4": {
-            "start": 3,
-            "end": 4
-        },
-        "motor_5": {
-            "start": 4,
-            "end": 5
-        },
-        "motor_6": {
-            "start": 5,
-            "end": 6
+        "gripper": {
+          "start": 5,
+          "end": 6
         }
     },
     "video": {
@@ -58,5 +26,10 @@
         "front_cam": {
             "original_key": "observation.images.secondary_0"
         }
+    },
+    "annotation": {
+        "human.task_description": {
+            "original_key": "task_index"
+        }
     }
 }