docs: Add display.rotate().

Author: microbit-carlos

docs/display.rst

@@ -72,6 +72,12 @@ Functions
     Note that the ``wait``, ``loop`` and ``monospace`` arguments must be specified
     using their keyword.
 
+.. py:function:: rotate(degrees)
+
+    Rotate the images shown on the display. The ``degrees`` parameter can be
+    any number, including a negative rotation, and it will be rounded to the
+    nearest multiple of 90 degrees.
+
 .. py:function:: on()
 
     Use on() to turn on the display.

docs/microbit_micropython_api.rst

@@ -76,6 +76,8 @@ The LED display is exposed via the `display` object::
     # scrolls a string across the display (more exciting than display.show for
     # written messages).
     display.scroll(string, delay=400)
+    # Rotates the display 0, 90, 180 or 270 degrees.
+    display.rotate(degrees)
 
 SoundEvent **V2**
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