Update README.md with new model card content

README.md

@@ -50,7 +50,7 @@ labels = [0, 3]
 
 # Pretrained classifier.
 classifier = keras_hub.models.RobertaClassifier.from_preset(
-    "${VARIATION_SLUG}",
+    "roberta_base_en",
     num_classes=4,
 )
 classifier.fit(x=features, y=labels, batch_size=2)
@@ -78,7 +78,7 @@ labels = [0, 3]
 
 # Pretrained classifier without preprocessing.
 classifier = keras_hub.models.RobertaClassifier.from_preset(
-    "${VARIATION_SLUG}",
+    "roberta_base_en",
     num_classes=4,
     preprocessor=None,
 )