Update README.md with new model card content

README.md

@@ -1,7 +1,7 @@
 ---
 library_name: keras-hub
 ---
-### Model Overview
+## Model Overview
 Instantiates the ResNet architecture. This model is supported in both KerasCV and KerasHub. KerasCV will no longer be actively developed, so please try to use KerasHub.
 
 **Reference**
@@ -41,7 +41,7 @@ The following model checkpoints are provided by the Keras team. Weights have bee
 | resnet_101_imagenet | 42.61M      | 101-layer ResNet model pre-trained on the ImageNet 1k dataset at a 224x224 resolution |
 | resnet_152_imagenet | 58.30M      | 52-layer ResNet model pre-trained on the ImageNet 1k dataset at a 224x224 resolution |
 
-### Example Usage
+## Example Usage
 ```python
     # Pretrained ResNet backbone.
     model = keras_hub.models.ResNetBackbone.from_preset("resnet_101_imagenet")