[py] fix typo in demo_wav2midi.py instructions (closes gh-355, thanks to @DJE98)

diff --git a/python/demos/demo_wav2midi.py b/python/demos/demo_wav2midi.py
index 8caa3ae..9496c5d 100755 (executable)
--- a/python/demos/demo_wav2midi.py
+++ b/python/demos/demo_wav2midi.py
@@ -3,7 +3,7 @@
 # Simple demo to extract notes from a sound file, and store them in a midi file
 # using mido.
 #
-# Install mido: `pip instal mido`
+# Install mido: `pip install mido`
 #
 # Documentation: https://mido.readthedocs.io/