doc/iodevices: reorganize TOC

Make the heading levels match the module. No subcategories, but say which devices are available on EV3 only.

doc/api/iodevices.rst

@@ -4,16 +4,14 @@
 .. automodule:: pybricks.iodevices
     :no-members:
 
-EV3
-##################
+LUMP Device
+^^^^^^^^^^^^^
+.. autoclass:: pybricks.iodevices.LUMPDevice
 
-The following classes are only available on the EV3.
+.. raw:: html
+
+   <h1>EV3 Only</h1>
+
+The classes listed below are **only available on the EV3**.
 
 .. include:: iodevices_ev3.inc
-
-Powered Up
-########################
-
-The following class is available on Powered Up hubs only.
-
-.. include:: iodevices_pup.inc

doc/api/iodevices_ev3.inc

@@ -65,6 +65,8 @@ UART Device
 DC Motor
 ^^^^^^^^^^^^
 
+This class can be used to control classic LEGO motors using converter cables.
+
 .. autoclass:: pybricks.builtins.DCMotor
     :noindex:
     :no-members:
@@ -72,7 +74,7 @@ DC Motor
     .. automethod:: pybricks.builtins.DCMotor.dc
         :noindex:
 
-Other ev3dev sensors
+Ev3dev sensors
 ^^^^^^^^^^^^^^^^^^^^^
 
 EV3 MicroPython is built on top of ev3dev, which means that a particular sensor

doc/api/iodevices_pup.inc

@@ -1,3 +0,0 @@
-LUMP Device
-^^^^^^^^^^^^^
-.. autoclass:: pybricks.iodevices.LUMPDevice

pybricks/iodevices.py

@@ -24,7 +24,8 @@ class LUMPDevice():
         pass
 
     def write(self, mode, values):
-        """Write values to the sensor.
+        """Write values to the sensor. Only selected sensors and modes support
+        this.
 
         Arguments:
             mode (``int``): Device mode.