Update README.md

Add description of encoder output to readme.

README.md

@@ -128,6 +128,12 @@ with torch.no_grad():
     output = model(input_values=inputs['input_values'],
                 attention_mask=inputs['attention_mask'],
                 output_hidden_states=True)
+
+    # output is a Wav2Vec2BaseModelOutput or tuple containing:
+    # last_hidden_state: torch.FloatTensor containing hidden states of the last layer of the model
+    # extract_features: torch.FloatTensor containing extracted features from the convolution downsampling layers
+    # hidden_states: tuple(torch.FloatTensor) containing hidden states of each layer of the model
+    # attentions: tuple(torch.FloatTensor) containing attention states of each layer of the model
 ```
 
 ## Downstream Use