snippet: Updated all snippet tags

Ensure all src C++ headers which have corresponding C++ examples have
doxygen tags which point to those examples.  Some were missing, some
were invalid, some needed to be updated to match the new example names.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/buzzer/buzzer.hpp

@@ -56,7 +56,7 @@ namespace upm {
      * frequencies based on the input voltage.
      *
      * @image html buzzer.jpg
-     * @snippet buzzer-sound.cxx Interesting
+     * @snippet buzzer.cxx Interesting
      */
 
     class Buzzer {