Add a usage example to the model card

README.md

@@ -10,6 +10,19 @@ license: cc-by-4.0
 pipeline_tag: audio-classification
 ---
 
+## Usage
+
+```python
+import librosa
+from espnet2.bin.spk_inference import Speech2Embedding
+
+speech2embedding = Speech2Embedding.from_pretrained(model_tag="espnet/voxcelebs12_ecapa_mel")
+# the speaker models are trained on 16 kHz mono; librosa gives that from
+# whatever the file holds
+speech, rate = librosa.load("audio.wav", sr=16000, mono=True)
+embedding = speech2embedding(speech)  # (1, embedding_dim)
+```
+
 ## ESPnet2 SPK model
 
 ### `espnet/voxcelebs12_ecapa_mel`