Improve `pitch_scale` descriptions in AudioStreamPlayer documentation

doc/classes/AudioStreamPlayer.xml

@@ -61,7 +61,7 @@
 			If the audio configuration has more than two speakers, this sets the target channels. See [enum MixTarget] constants.
 		</member>
 		<member name="pitch_scale" type="float" setter="set_pitch_scale" getter="get_pitch_scale" default="1.0">
-			Changes the pitch and the tempo of the audio.
+			The pitch and the tempo of the audio, as a multiplier of the audio sample's sample rate.
 		</member>
 		<member name="playing" type="bool" setter="_set_playing" getter="is_playing" default="false">
 			If [code]true[/code], audio is playing.

doc/classes/AudioStreamPlayer2D.xml

@@ -67,7 +67,7 @@
 			Maximum distance from which audio is still hearable.
 		</member>
 		<member name="pitch_scale" type="float" setter="set_pitch_scale" getter="get_pitch_scale" default="1.0">
-			Changes the pitch and the tempo of the audio.
+			The pitch and the tempo of the audio, as a multiplier of the audio sample's sample rate.
 		</member>
 		<member name="playing" type="bool" setter="_set_playing" getter="is_playing" default="false">
 			If [code]true[/code], audio is playing.

doc/classes/AudioStreamPlayer3D.xml

@@ -91,7 +91,7 @@
 			Decides if audio should pause when source is outside of [member max_distance] range.
 		</member>
 		<member name="pitch_scale" type="float" setter="set_pitch_scale" getter="get_pitch_scale" default="1.0">
-			Changes the pitch and the tempo of the audio.
+			The pitch and the tempo of the audio, as a multiplier of the audio sample's sample rate.
 		</member>
 		<member name="playing" type="bool" setter="_set_playing" getter="is_playing" default="false">
 			If [code]true[/code], audio is playing.