merge libmaple docs ("leaflabs-docs") into ./docs

In the past, libample documentation was forked out of this repository
because the documentation had increased in scope. For the librambutan,
and the rambutan project in general, we will try to keep documentation
closer to the source code, so the librambutan-specific documentation
should live here. Other sections of leaflabs-docs will be culled in a
following commit.

This merge attempts to maintain history by using a subtree strategy.
Followed directions at:

    http://nuclearsquid.com/writings/subtree-merging-and-you/

Full history for files should be accessible using the "--follow" flag to
git log, eg:

    git log --follow docs/source/adc.rst

It should be possible to pull patches from leaflabs-docs with:

    git pull -s subtree leaflabs-docs master

... at least until the docs in this repository diverge significantly.

1 files changed, 58 insertions, 0 deletions

diff --git a/docs/source/lang/unimplemented/tone.rst b/docs/source/lang/unimplemented/tone.rst
new file mode 100644
index 0000000..13d581e
--- /dev/null
+++ b/docs/source/lang/unimplemented/tone.rst
@@ -0,0 +1,58 @@
+.. _lang-tone:
+
+tone()
+======
+
+Description
+-----------
+
+Generates a square wave of the specified frequency (and 50% duty
+cycle) on a pin. A duration can be specified, otherwise the wave
+continues until a call to
+`noTone <http://arduino.cc/en/Reference/NoTone>`_\ (). The pin can be
+connected to a piezo buzzer or other speaker to play tones.
+
+Only one tone can be generated at a time. If a tone is already
+playing on a different pin, the call to tone() will have no effect.
+If the tone is playing on the same pin, the call will set its
+frequency.
+
+Use of the tone() function will interfere with PWM output on pins 3
+and 11 (on boards other than the Mega).
+
+**NOTE:** if you want to play different pitches on multiple pins,
+you need to call noTone() on one pin before calling tone() on the
+next pin.
+
+Syntax
+------
+
+tone(pin, frequency)
+tone(pin, frequency, duration)
+
+Parameters
+----------
+
+pin: the pin on which to generate the tone
+
+frequency: the frequency of the tone in hertz
+
+duration: the duration of the tone in milliseconds (optional)
+
+Returns
+-------
+
+nothing
+
+See Also
+--------
+
+-  `noTone <http://arduino.cc/en/Reference/NoTone>`_\ ()
+-  `analogWrite <http://arduino.cc/en/Reference/AnalogWrite>`_\ ()
+-  `Tutorial:Tone <http://arduino.cc/en/Tutorial/Tone>`_
+-  `Tutorial:Pitch follower <http://arduino.cc/en/Tutorial/Tone2>`_
+-  `Tutorial:Simple Keyboard <http://arduino.cc/en/Tutorial/Tone3>`_
+-  `Tutorial: multiple tones <http://arduino.cc/en/Tutorial/Tone4>`_
+-  `Tutorial: PWM <http://arduino.cc/en/Tutorial/PWM>`_
+
+.. include:: /arduino-cc-attribution.txt