Generic docs need reST

Conversion of all docs to reST so that the generic docs can link easily
with the rest of the docs.

docs/api_input.rst

@@ -0,0 +1,59 @@
+=============
+Input Devices
+=============
+
+.. currentmodule:: gpiozero
+
+These input device component interfaces have been provided for simple use of
+everyday components. Components must be wired up correctly before use in code.
+
+.. note::
+
+    All GPIO pin numbers use Broadcom (BCM) numbering. See the :doc:`recipes`
+    page for more information.
+
+
+Button
+======
+
+.. autoclass:: Button(pin, pull_up=True, bounce_time=None)
+    :members: wait_for_press, wait_for_release, pin, is_pressed, pull_up, when_pressed, when_released
+
+
+Motion Sensor (PIR)
+===================
+
+.. autoclass:: MotionSensor(pin, queue_len=1, sample_rate=10, threshold=0.5, partial=False)
+    :members: wait_for_motion, wait_for_no_motion, pin, motion_detected, when_motion, when_no_motion
+
+
+Light Sensor (LDR)
+==================
+
+.. autoclass:: LightSensor(pin, queue_len=5, charge_time_limit=0.01, threshold=0.1, partial=False)
+    :members: wait_for_light, wait_for_dark, pin, light_detected, when_light, when_dark
+
+Analog to Digital Converters (ADC)
+==================================
+
+.. autoclass:: MCP3004
+    :members: bus, device, channel, value, differential
+
+.. autoclass:: MCP3008
+    :members: bus, device, channel, value, differential
+
+.. autoclass:: MCP3204
+    :members: bus, device, channel, value, differential
+
+.. autoclass:: MCP3208
+    :members: bus, device, channel, value, differential
+
+.. autoclass:: MCP3301
+    :members: bus, device, value
+
+.. autoclass:: MCP3302
+    :members: bus, device, channel, value, differential
+
+.. autoclass:: MCP3304
+    :members: bus, device, channel, value, differential
+