Fixes nav for /lite/models pages.

PiperOrigin-RevId: 236941300

tensorflow/lite/g3doc/_book.yaml

@@ -94,30 +94,22 @@ upper_tabs:
       contents:
       - title: "Overview"
         path: /lite/models/
-      - title: "Image classification"
-        section:
-        - title: "Overview"
-          path: /lite/models/image_classification/overview
-        - title: "Android"
-          path: /lite/models/image_classification/android
-        - title: "iOS"
-          path: /lite/models/image_classification/ios
+      - heading: "Image classification"
+      - title: "Overview"
+        path: /lite/models/image_classification/overview
+      - title: "Android"
+        path: /lite/models/image_classification/android
+      - title: "iOS"
+        path: /lite/models/image_classification/ios
+      - heading: "Other techniques"
       - title: "Object detection"
-        section:
-        - title: "Overview"
-          path: /lite/models/object_detection/overview
+        path: /lite/models/object_detection/overview
       - title: "Pose estimation"
-        section:
-        - title: "Overview"
-          path: /lite/models/pose_estimation/overview
+        path: /lite/models/pose_estimation/overview
       - title: "Segmentation"
-        section:
-        - title: "Overview"
-          path: /lite/models/segmentation/overview
+        path: /lite/models/segmentation/overview
       - title: "Smart reply"
-        section:
-        - title: "Overview"
-          path: /lite/models/smart_reply/overview
+        path: /lite/models/smart_reply/overview
 
     - name: "API"
       skip_translation: true