inserting macros instead of hard coded board names

docs/reference/basic/forever.md

@@ -35,7 +35,7 @@ basic.forever(() => {
 
 The following example keeps showing the [number](/reference/types/number) stored in a global variable.
 When you press button `A`, the number gets bigger.
-You can use a program like this to count things with your BBC micro:bit.
+You can use a program like this to count things with your @boardname@.
 
 ```blocks
 let num = 0

docs/reference/basic/show-animation.md

@@ -21,7 +21,7 @@ basic.showAnimation(`
 
 In this animation, each row is 15 spaces wide because
 there are three frames in the animation, and each frame is
-five spaces wide, just like the screen on the BBC micro:bit.
+five spaces wide, just like the screen on the @boardname@.
 
 ```blocks
 basic.showAnimation(`