Attempt to fix example syntax sections

Something fishy going on with the Markdown for the code examples in the
Notes page. Might be down to the indentation of the list item's content?
The vim markdown parser seems to think so anyway; let's see what
pythonhosted.org says ...

docs/notes.md

@@ -2,88 +2,88 @@
 
 1. **BCM pin numbering**
 
-    This library uses Broadcom (BCM) pin numbering for the GPIO pins, as
-    opposed to BOARD. Unlike the `RPi.GPIO` library, this is not configurable.
+   This library uses Broadcom (BCM) pin numbering for the GPIO pins, as
+   opposed to BOARD. Unlike the `RPi.GPIO` library, this is not configurable.
 
-    Any pin marked `GPIO` can be used for generic components.
+   Any pin marked `GPIO` can be used for generic components.
 
-    The BCM pin layout is as follows:
+   The BCM pin layout is as follows:
 
-    |            |            |
-    |-----------:|:-----------|
-    |    3V3     | 5V         |
-    |  **GPIO2** | 5V         |
-    |  **GPIO3** | GND        |
-    |  **GPIO4** | **GPIO14** |
-    |        GND | **GPIO15** |
-    | **GPIO17** | **GPIO18** |
-    | **GPIO27** | GND        |
-    | **GPIO22** | **GPIO23** |
-    |        3V3 | **GPIO24** |
-    | **GPIO10** | GND        |
-    |  **GPIO9** | **GPIO25** |
-    | **GPIO11** | **GPIO8**  |
-    |        GND | **GPIO7**  |
-    |        DNC | DNC        |
-    |  **GPIO5** | GND        |
-    |  **GPIO6** | **GPIO12** |
-    | **GPIO13** | GND        |
-    | **GPIO19** | **GPIO16** |
-    | **GPIO26** | **GPIO20** |
-    |        GND | **GPIO21** |
+   |            |            |
+   |-----------:|:-----------|
+   |    3V3     | 5V         |
+   |  **GPIO2** | 5V         |
+   |  **GPIO3** | GND        |
+   |  **GPIO4** | **GPIO14** |
+   |        GND | **GPIO15** |
+   | **GPIO17** | **GPIO18** |
+   | **GPIO27** | GND        |
+   | **GPIO22** | **GPIO23** |
+   |        3V3 | **GPIO24** |
+   | **GPIO10** | GND        |
+   |  **GPIO9** | **GPIO25** |
+   | **GPIO11** | **GPIO8**  |
+   |        GND | **GPIO7**  |
+   |        DNC | DNC        |
+   |  **GPIO5** | GND        |
+   |  **GPIO6** | **GPIO12** |
+   | **GPIO13** | GND        |
+   | **GPIO19** | **GPIO16** |
+   | **GPIO26** | **GPIO20** |
+   |        GND | **GPIO21** |
 
-    - *GND = Ground*
-    - *3V3 = 3.3 Volts*
-    - *5V = 5 Volts*
-    - *DNC = Do not connect (special use pins)*
+   - *GND = Ground*
+   - *3V3 = 3.3 Volts*
+   - *5V = 5 Volts*
+   - *DNC = Do not connect (special use pins)*
 
 2. **Wiring**
 
-    All components must be wired up correctly before using with this library.
+   All components must be wired up correctly before using with this library.
 
 3. **Keep your program alive with `signal.pause`**
 
-    The following program looks like it should turn an LED on:
+   The following program looks like it should turn an LED on:
 
-    ```python
-    from gpiozero import led
+   ```python
+   from gpiozero import led
 
-    led = LED(2)
+   led = LED(2)
 
-    led.on()
-    ```
+   led.on()
+   ```
 
-    And it does, if you're using the Python shell, IPython shell or IDLE shell,
-    but if you saved this program as a Python file and ran it, it would flash
-    on for a moment then the program would end and it would turn off.
+   And it does, if you're using the Python shell, IPython shell or IDLE shell,
+   but if you saved this program as a Python file and ran it, it would flash
+   on for a moment then the program would end and it would turn off.
 
-    The following file includes an intentional `pause` to keep the program
-    alive:
+   The following file includes an intentional `pause` to keep the program
+   alive:
 
-    ```python
-    from gpiozero import LED
-    from signal import pause
+   ```python
+   from gpiozero import LED
+   from signal import pause
 
-    led = LED(2)
+   led = LED(2)
 
-    led.on()
+   led.on()
 
-    pause()
-    ```
+   pause()
+   ```
 
-    Now running the program will stay running, leaving the LED on, until it is
-    forced to quit.
+   Now running the program will stay running, leaving the LED on, until it is
+   forced to quit.
 
-    Similarly, when setting up callbacks on button presses or other input
-    devices, the program needs to be running for the events to be detected:
+   Similarly, when setting up callbacks on button presses or other input
+   devices, the program needs to be running for the events to be detected:
 
-    ```python
-    from gpiozero import Button
-    from signal import pause
+   ```python
+   from gpiozero import Button
+   from signal import pause
 
-    button = Button(2)
+   button = Button(2)
 
-    button.when_pressed = lambda: print("Button was pressed!")
+   button.when_pressed = lambda: print("Button was pressed!")
 
-    pause()
-    ```
+   pause()
+   ```