fix: update dataset top page

Signed-off-by: Ryohsuke Mitsudome <[email protected]>

docs/datasets/index.md

@@ -2,11 +2,5 @@
 
 Autoware partners provide datasets for testing and development. These datasets are available for download here.
 
-## Raw Sensor Datasets
-
-We provide raw data from the sensors attached to a vehicle.
-The data is mainly used to learn how data should be provided to Autoware or to test functions of Autoware.
-
-## Annotated Datasets
-
-We provide annoated datasets for training/evaluating machine learning based modules.
+ *  [Raw Sensor Datasets](./raw-sensor-data/index.md): raw data from sensors attached to a vehicle. They are mainly used to learn how data should be provided to Autoware or test functions of Autoware.
+ *  [Annotated Datasets](./annotated-data/index.md): Annotated datasets for training/evaluating machine learning based functions.