readme: update TensorBoard info

Unfortunately, TensorBoard logs are not available for hmBERT based models.

README.md

@@ -61,7 +61,7 @@ And report micro F1-score on development set:
 [19]: https://hf.co/hmbench/hmbench-hipe2020-de-hmbert-bs4-wsFalse-e10-lr5e-05-poolingfirst-layers-1-crfFalse-4
 [20]: https://hf.co/hmbench/hmbench-hipe2020-de-hmbert-bs4-wsFalse-e10-lr5e-05-poolingfirst-layers-1-crfFalse-5
 
-The [training log](training.log) and TensorBoard logs are also uploaded to the model hub.
+The [training log](training.log) and TensorBoard logs (only for hmByT5 and hmTEAMS based models) are also uploaded to the model hub.
 
 More information about fine-tuning can be found [here](https://github.com/stefan-it/hmBench).