updating tag for exbert viz (#8408)

Author: smanjil

model_cards/smanjil/German-MedBERT/README.md

@@ -1,7 +1,13 @@
 ---
 language: de
+tags: 
+- exbert
 ---
 
+<a href="https://huggingface.co/exbert/?model=smanjil/German-MedBERT">
+	<img width="300px" src="https://cdn-media.huggingface.co/exbert/button.png">
+</a>
+
 # German Medical BERT
 
 This is a fine-tuned model on Medical domain for German language and based on German BERT.