Update README.md

README.md

@@ -34,6 +34,8 @@ RWKV-4-Pile-430M-20220808-8066.pth : Trained on the Pile for 333B tokens.
 * SC2016 acc 63.87%
 * Hellaswag acc_norm 40.90%
 
+## Warning: 4 / 4a / 4b models ARE NOT compatible!!! Use RWKV-4 unless you know what you are doing.
+
 With tiny attention (--tiny_att_dim 512 --tiny_att_layer 18):
 RWKV-4a-Pile-433M-20221223-8039.pth
 * Pile loss 2.2394