docs: Alphabetise microbit module & use docstring notations. (#734)

* docs: Reorganise microbit module entries to be listed alphabetically.

* docs: Update microbit module docs to use docstring notations.

docs/microbit.rst

@@ -13,36 +13,38 @@ Functions
 
 .. py:function:: panic(n)
 
-    Enter a panic mode. Requires restart. Pass in an arbitrary integer <= 255
-    to indicate a status::
+    Enter a panic mode that stops all execution, scrolls an error code in
+    the micro:bit display and requires restart::
 
         microbit.panic(255)
 
+    :param n: An arbitrary integer between 0 and 255 to indicate an error code.
+
 
 .. py:function:: reset()
 
     Restart the board.
 
 
-.. py:function:: sleep(n)
-
-    Wait for ``n`` milliseconds. One second is 1000 milliseconds, so::
+.. py:function:: running_time()
 
-        microbit.sleep(1000)
+    :returns: The number of milliseconds since the board was switched on or
+        restarted.
 
-    will pause the execution for one second.  ``n`` can be an integer or
-    a floating point number.
 
+.. py:function:: sleep(n)
 
-.. py:function:: running_time()
+    Wait for ``n`` milliseconds. One second is 1000 milliseconds, so
+    ``microbit.sleep(1000)`` will pause the execution for one second.
 
-    Return the number of milliseconds since the board was switched on or
-    restarted.
+    :param n: An integer or floating point number indicating the number of
+        milliseconds to wait.
 
 
 .. py:function:: temperature()
 
-    Return the temperature of the micro:bit in degrees Celcius.
+    :returns: An integer with the temperature of the micro:bit in degrees
+        Celcius.
 
 
 Attributes
@@ -70,9 +72,9 @@ Modules
 .. toctree::
     :maxdepth: 1
 
-    display.rst
-    uart.rst
-    spi.rst
-    i2c.rst
     accelerometer.rst
     compass.rst
+    display.rst
+    i2c.rst
+    spi.rst
+    uart.rst