Added description and measurement

doc/classes/AudioStream.xml

@@ -16,7 +16,7 @@
 			<return type="float">
 			</return>
 			<description>
-				Returns the length of the audio stream, in seconds.
+				Returns the length of the audio stream in seconds.
 			</description>
 		</method>
 	</methods>

doc/classes/AudioStreamPlayer.xml

@@ -17,7 +17,7 @@
 			<return type="float">
 			</return>
 			<description>
-				Returns the position in the [AudioStream].
+				Returns the position in the [AudioStream] in seconds.
 			</description>
 		</method>
 		<method name="play">