Mention listener node in AudioStreamPlayer3D description

(cherry picked from commit 51367c1bcf8eb79d81f5a4b4e35285e29b1ca623)

doc/classes/AudioStreamPlayer3D.xml

@@ -5,6 +5,7 @@
 	</brief_description>
 	<description>
 		Plays a sound effect with directed sound effects, dampens with distance if needed, generates effect of hearable position in space.
+		By default, audio is heard from the camera position. This can be changed by adding a [Listener] node to the scene and enabling it by calling [method Listener.make_current] on it.
 	</description>
 	<tutorials>
 		<link>https://docs.godotengine.org/en/latest/tutorials/audio/audio_streams.html</link>