Update changelog and some small docs changes

Author: bennuttall

docs/changelog.rst

@@ -49,11 +49,15 @@ Release 1.5.0 (2019-02-12)
   (thanks to Jeevan M R for the latter). (`#532`_, `#714`_)
 * Added support for `colorzero`_ with :class:`RGBLED` (this adds a new
   dependency). (`#655`_)
-* Added :class:`TonalBuzzer` class with musical notation API :class:`Tone`.
-  (`#681`_, `#717`_)
+* Added :class:`TonalBuzzer` with :class:`Tone` API for specifying frequencies
+  raw or via MIDI or musical notes. (`#681`_, `#717`_)
 * Added :class:`PiHutXmasTree`. (`#502`_)
 * Added :class:`PumpkinPi` and :class:`JamHat` (thanks to Claire Pollard).
   (`#680`_, `#681`_, `#717`_)
+* Ensured gpiozero can be imported without a valid pin factory set. (`#591`_,
+  `#713`_)
+* Reduced import time by not computing default pin factory at the point of
+  import. (`#675`_, `#722`_)
 * Added support for various pin numbering mechanisms. (`#470`_)
 * :class:`Motor` instances now use :class:`DigitalOutputDevice` for non-PWM
   pins.
@@ -89,6 +93,10 @@ Release 1.5.0 (2019-02-12)
 .. _#717: https://github.com/RPi-Distro/python-gpiozero/issues/717
 .. _#680: https://github.com/RPi-Distro/python-gpiozero/issues/680
 .. _#502: https://github.com/RPi-Distro/python-gpiozero/issues/502
+.. _#591: https://github.com/RPi-Distro/python-gpiozero/issues/591
+.. _#713: https://github.com/RPi-Distro/python-gpiozero/issues/713
+.. _#675: https://github.com/RPi-Distro/python-gpiozero/issues/675
+.. _#722: https://github.com/RPi-Distro/python-gpiozero/issues/722
 .. _#470: https://github.com/RPi-Distro/python-gpiozero/issues/470
 .. _#481: https://github.com/RPi-Distro/python-gpiozero/issues/481
 .. _#366: https://github.com/RPi-Distro/python-gpiozero/issues/366

gpiozero/input_devices.py

@@ -765,9 +765,10 @@ class DistanceSensor(SmoothedInputDevice):
 
     .. note::
 
-        For improved accuracy, use the pigpio pin driver rather than the
-        default RPi.GPIO driver (pigpio uses DMA sampling for much more precise
-        edge timing). See :ref:`changing-pin-factory` for further information.
+        For improved accuracy, use the pigpio pin driver rather than the default
+        RPi.GPIO driver (pigpio uses DMA sampling for much more precise edge
+        timing). This is particularly relevant if you're using Pi 1 or Pi Zero.
+        See :ref:`changing-pin-factory` for further information.
 
     :type echo: int or str
     :param echo:

gpiozero/tones.py

@@ -30,7 +30,7 @@ class to easily represent musical tones. The class can be constructed in a
     representation of a musical note.
 
     All the following constructors are equivalent ways to construct the typical
-    tuning note, `concert A`_ at 440Hz which is MIDI note #69):
+    tuning note, `concert A`_ at 440Hz, which is MIDI note #69:
 
         >>> from gpiozero.tones import Tone
         >>> Tone(440.0)