Add example wav and update code example

README.md

@@ -38,13 +38,21 @@ Please notice that we encourage you to read our tutorials and learn more about
 To use the mimic-loss-trained model for enhancement, use the following simple code:
 
 ```python
+import torch
 from speechbrain.pretrained import SpectralMaskEnhancement
 
 enhance_model = SpectralMaskEnhancement.from_hparams(
     source="speechbrain/metricgan-plus-voicebank",
     savedir="pretrained_models/metricgan-plus-voicebank",
 )
-enhance_model.enhance_file("/path/to/file.wav")
+
+# Load and add fake batch dimension
+noisy = enhance_model.load_audio(
+    "speechbrain/metricgan-plus-voicebank/example.wav"
+).unsqueeze(0)
+
+# Add relative length tensor
+enhance_model.enhance_batch(noisy, lengths=torch.tensor([1.]))
 ```
 
 ## Referencing MetricGAN+