Update config.json

config.json

@@ -11,6 +11,7 @@
   "max_position_embeddings": 512,
   "num_attention_heads": 12,
   "num_hidden_layers": 12,
+  "pad_token_id": 3,
   "type_vocab_size": 2,
   "vocab_size": 30000
-}
+}