pxt-microbit Accessibility PR (#529)

* Accessibility changes

docs/reference/input/temperature.md

@@ -7,18 +7,18 @@ The @boardname@ can find the temperature nearby by checking how hot its computer
 input.temperature();
 ```
 
-### Returns
+## Returns
 
 * a [Number](/types/number) that means the Celsius temperature.
 
-### How does it work?
+## How does it work?
 
 The @boardname@ checks how hot its CPU (main computer chip) is.
 Because the @boardname@ does not usually get very hot, the temperature of the CPU
 is usually close to the temperature of wherever you are.
 The @boardname@ might warm up a little if you make it work hard, though!
 
-### Example: @boardname@ thermometer
+## Example: @boardname@ thermometer
 
 The following example uses `temperature` and `show number` to show the temperature of the room.
 
@@ -28,7 +28,7 @@ basic.forever(() => {
     basic.showNumber(temp)
 })
 ```
-### Example: Fahrenheit thermometer
+## Example: Fahrenheit thermometer
 
 This program measures the temperature using Fahrenheit degrees.
 Fahrenheit is a way of measuring temperature that is commonly used in the United States.
@@ -43,16 +43,16 @@ basic.forever(() => {
 })
 ```
 
-### ~hint
+## ~hint
 
 Try comparing the temperature your @boardname@ shows to a real thermometer in the same place.
 You might be able to figure out how much to subtract from the number the @boardname@
 shows to get the real temperature. Then you can change your program so the @boardname@ is a 
 better thermometer.
 
-### ~
+## ~
 
-### See also
+## See also
 
 [compass-heading](/reference/input/compass-heading), [acceleration](/reference/input/acceleration)