Fix multiple occurences of typo "an simple" to "a simple"

examples/audio/03-load-wav/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 creates an simple audio stream for playing sound, and
+This example code creates a simple audio stream for playing sound, and
 loads a .wav file that is pushed through the stream in a loop.
 

examples/audio/03-load-wav/load-wav.c

@@ -1,5 +1,5 @@
 /*
- * This example code creates an simple audio stream for playing sound, and
+ * This example code creates a simple audio stream for playing sound, and
  * loads a .wav file that is pushed through the stream in a loop.
  *
  * This code is public domain. Feel free to use it for any purpose!