Tweak to API documentation and "it may not work" section, pomodoro timer bugfix

Author: c-mart

docs/microbit_micropython_api.rst

@@ -223,7 +223,7 @@ The accelerometer is accessed via the ``accelerometer`` object::
     accelerometer.get_y()
     # read the Z axis of the device. Measured in milli-g.
     accelerometer.get_z()
-    # get all three X, Y and Z readings (listed in that order).
+    # get tuple of all three X, Y and Z readings (listed in that order).
     accelerometer.get_values()
     # return the name of the current gesture.
     accelerometer.current_gesture()

docs/tutorials/hello.rst

@@ -64,3 +64,9 @@ change the scroll method's argument.
     in a way that MicroPython can't understand. Check you're not missing any
     special characters like ``"`` or ``:``. It's like putting. a full stop in
     the middle of a sentence. It's hard to understand exactly what you mean.
+
+    Your microbit may stop responding: you cannot flash new code to it or
+    enter commands into the REPL. If this happens, try power cycling it. That
+    is, unplug the USB cable (and battery cable if it's connected), then plug
+    the cable back in again. You may also need to quit and re-start your code
+    editor application.

examples/pomodoro.py

@@ -41,7 +41,7 @@ def run_timer(seconds, LED_state):
         if time - timer >= interval:
             timer = time
             x, y = index_to_xy(intervals_remaining - 1)
-            display.image.set_pixel(x, y, LED_state)
+            display.set_pixel(x, y, LED_state)
             intervals_remaining -= 1
 
 
@@ -65,4 +65,3 @@ def run_timer(seconds, LED_state):
 
 print("finished\n")
 print("Press the reset button to restart timer.")
-