Add API docs for Tone

and ditch the fancy UTF-8 sharp/flat chars because of
readthedocs/readthedocs.org#1556 ... again

docs/api_output.rst

@@ -37,13 +37,13 @@ Buzzer
 ======
 
 .. autoclass:: Buzzer(pin, \*, active_high=True, initial_value=False, pin_factory=None)
-    :members: on, off, toggle, beep, pin, is_active
+    :members: on, off, toggle, beep, pin, is_active, value
 
 TonalBuzzer
 ===========
 
 .. autoclass:: TonalBuzzer(pin, \*, initial_value=None, mid_note='A4', octaves=1, pin_factory=None)
-    :members: play, stop, note_value, is_active, octaves, min_note, mid_note, max_note
+    :members: play, stop, octaves, min_tone, mid_tone, max_tone, tone, is_active, value
 
 Motor
 =====

docs/api_tones.rst

@@ -0,0 +1,18 @@
+===========
+API - Tones
+===========
+
+.. module:: gpiozero.tones
+
+GPIO Zero includes a :class:`Tone` class intended for use with the
+:class:`~gpiozero.TonalBuzzer`. This class is in the ``tones`` module of GPIO
+Zero and is typically imported as follows::
+
+    from gpiozero.tones import Tone
+
+
+Tone
+====
+
+.. autoclass:: Tone
+    :members:

docs/index.rst

@@ -26,6 +26,7 @@ Table of Contents
     api_internal
     api_generic
     api_tools
+    api_tones
     api_info
     api_pins
     api_exc

gpiozero/tones.py

@@ -116,8 +116,8 @@ def from_note(cls, note):
 
         For example `concert A`_, the typical tuning note at 440Hz, would be
         represent as "A4". One semi-tone above this would be "A#4" or
-        alternatively "Bb4". Unicode representations are also accepted, e.g.
-        "A♯4" or "B♭4".
+        alternatively "Bb4". Unicode representations of sharp and flat are also
+        accepted.
         """
         if isinstance(note, bytes):
             note = note.decode('ascii')