[tts] update finetune yaml and readme (#2418)

* update yaml and readme, test=tts

examples/other/tts_finetune/tts3/README.md

@@ -221,3 +221,5 @@ optional arguments:
 
 ### Tips
 If you want to get better audio quality, you can use more audios to finetune.
+More finetune results can be found on [finetune-fastspeech2-for-csmsc](https://paddlespeech.readthedocs.io/en/latest/tts/demo.html#finetune-fastspeech2-for-csmsc).
+The results show the effect on csmsc_mini: Freeze encoder > Non Frozen > Freeze encoder && duration_predictor.

examples/other/tts_finetune/tts3/finetune.yaml

@@ -9,4 +9,4 @@ num_snapshots: -1
 
 # frozen_layers should be a list
 # if you don't need to freeze, set frozen_layers to []
-frozen_layers: ["encoder", "duration_predictor"]
+frozen_layers: ["encoder"]