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/uartat/uartat.hpp

@@ -41,6 +41,7 @@ namespace upm {
      * @comname Generic AT Command Based UART Device
      * @type other
      * @con uart
+     * @snippet uartat-le910.cxx Interesting
      *
      * @brief API for a Generic AT command based UART device
      *