[Morse] Hide structure from Doxygen

src/protocols/Morse.cpp

@@ -1,10 +1,16 @@
 #include "Morse.h"
 
 // structure to save data about character Morse code
+/*!
+  \cond RADIOLIB_DOXYGEN_HIDDEN
+*/
 struct Morse_t {
   char c;                                             // ASCII character
   const char* m;                                      // Morse code representation
 };
+/*!
+  \endcond
+*/
 
 // array of all Morse code characters
 static const Morse_t MorseTable[MORSE_LENGTH] = {