Documenting that the python ASR example app only supports audio files with 16000Hz sampling rate.

Change-Id: Ib36cf059fe1d187204f73352eb91bf7134757221
Signed-off-by: Éanna Ó Catháin <eanna.ocathain@arm.com>
diff --git a/python/pyarmnn/examples/speech_recognition/README.md b/python/pyarmnn/examples/speech_recognition/README.md
index f92bae6..7af1b18 100644
--- a/python/pyarmnn/examples/speech_recognition/README.md
+++ b/python/pyarmnn/examples/speech_recognition/README.md
@@ -53,6 +53,7 @@
 ```bash
 $ python run_audio_file.py --audio_file_path <path/to/your_audio> --model_file_path <path/to/your_model> --labels_file_path <path/to/your_labels>
 ```
+Please ensure that your audio file has a sampling rate of 16000Hz.
 
 You may also add the optional flags: