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/grove/groverotary.hpp

@@ -51,7 +51,7 @@ namespace upm {
  * to do the same relative to the center of the knob's range.
  *
  * @image html rotaryencoder.jpg
- * @snippet groverotary.cxx Interesting
+ * @snippet grove-groverotary.cxx Interesting
  */
 class GroveRotary: public Grove {
     public: