docs(README): added basic save to MIDI info

README.rst

@@ -53,7 +53,7 @@ Following a process created by the composer Arnold Schoenberg, this library
 computes a matrix to create twelve-tone serialism melodies which compose each
 of the 12 semitones of the chromatic scale with equal importance.
 
-
+* Save your compositions to MIDI
 * Free software: BSD license
 
 Installation
@@ -75,6 +75,17 @@ Quick Start
     ['C# / Db', 'A# / Bb', 'F', 'D', 'G# / Ab', 'D# / Eb', 'F# / Gb',
         'A', 'C', 'G', 'B', 'E']
 
+After you have composed a matrix of tone rows, you can save the composition to
+MIDI:
+
+::
+
+    >>> c.compose()
+    >>> c.save_to_midi(filename='TWELVE_TONE.mid')
+
+The new MIDI file will be created in your current working directory. If you do
+not specify a `filename` for your file, it will default to `example.mid`.
+
 Documentation
 =============