SoundTransform: clean up docs and add a couple of examples

It's easy to try soundChannel.soundTransform.volume = value and think it is broken, so these examples show that you need to set soundChannel.soundTransform to a value

src/openfl/media/SoundTransform.hx

@@ -15,40 +15,74 @@ package openfl.media;
 @:final class SoundTransform
 {
 	/**
-		A value, from 0(none) to 1(all), specifying how much of the left input
+		A value, from 0 (none) to 1 (all), specifying how much of the left input
 		is played in the left speaker.
 	**/
 	public var leftToLeft:Float;
 
 	/**
-		A value, from 0(none) to 1(all), specifying how much of the left input
+		A value, from 0 (none) to 1 (all), specifying how much of the left input
 		is played in the right speaker.
 	**/
 	public var leftToRight:Float;
 
 	/**
-		The left-to-right panning of the sound, ranging from -1(full pan left) to
-		1(full pan right). A value of 0 represents no panning(balanced center
-		between right and left).
+		The left-to-right panning of the sound, ranging from -1 (full pan left)
+		to 1 (full pan right). A value of 0 represents no panning (balanced
+		center between right and left).
+
+		The following example sets the pan to 0.5 (half pan right) when
+		starting to play a Sound.
+
+		```haxe
+		var transform = new SoundTransform(1.0, 0.5);
+		var soundChannel = sound.play(0, 0, transform);
+		```
+
+		The following example sets the pan to -1 (full pan left) for a
+		SoundChannel that is currently playing.
+
+		```haxe
+		var transform = soundChannel.soundTransform;
+		transform.pan = -1.0;
+		soundChannel.soundTransform = transform;
+		```
 
 		@see [Controlling sound volume and panning](https://books.openfl.org/openfl-developers-guide/working-with-sound/controlling-sound-volume-and-panning.html)
 	**/
 	public var pan:Float;
 
 	/**
-		A value, from 0(none) to 1(all), specifying how much of the right input
-		is played in the left speaker.
+		A value, from 0 (none) to 1 (all), specifying how much of the right
+		input is played in the left speaker.
 	**/
 	public var rightToLeft:Float;
 
 	/**
-		A value, from 0(none) to 1(all), specifying how much of the right input
-		is played in the right speaker.
+		A value, from 0 (none) to 1 (all), specifying how much of the right
+		input is played in the right speaker.
 	**/
 	public var rightToRight:Float;
 
 	/**
-		The volume, ranging from 0(silent) to 1(full volume).
+		The volume, ranging from 0 (silent) to 1 (full volume).
+
+		The following example sets the volume to 0.5 (half volume) when
+		starting to play a Sound.
+
+		```haxe
+		var transform = new SoundTransform(0.5);
+		var soundChannel = sound.play(0, 0, transform);
+		```
+
+		The following example sets the volume to 0.0 (silent) for a
+		SoundChannel that is currently playing.
+
+		```haxe
+		var transform = soundChannel.soundTransform;
+		transform.volume = 0.0;
+		soundChannel.soundTransform = transform;
+		```
 
 		@see [Controlling sound volume and panning](https://books.openfl.org/openfl-developers-guide/working-with-sound/controlling-sound-volume-and-panning.html)
 	**/
@@ -57,10 +91,10 @@ package openfl.media;
 	/**
 		Creates a SoundTransform object.
 
-		@param vol     The volume, ranging from 0(silent) to 1(full volume).
+		@param vol     The volume, ranging from 0 (silent) to 1 (full volume).
 		@param panning The left-to-right panning of the sound, ranging from -1
-					  (full pan left) to 1(full pan right). A value of 0
-					   represents no panning(center).
+					   (full pan left) to 1 (full pan right). A value of 0
+					   represents no panning (center).
 	**/
 	public function new(vol:Float = 1, panning:Float = 0)
 	{