comments: Fixed a few typos I ran into in the audio code.

examples/audio/04-multiple-streams/README.txt

@@ -1,5 +1,5 @@
 If you're running this in a web browser, you need to click the window before you'll hear anything!
 
-This example code loads two .wav files, puts them an audio streams and binds
+This example code loads two .wav files, puts them in audio streams and binds
 them for playback, repeating both sounds on loop. This shows several streams
 mixing into a single playback device.

examples/audio/04-multiple-streams/multiple-streams.c

@@ -1,5 +1,5 @@
 /*
- * This example code loads two .wav files, puts them an audio streams and
+ * This example code loads two .wav files, puts them in audio streams and
  * binds them for playback, repeating both sounds on loop. This shows several
  * streams mixing into a single playback device.
  *