[RTTY] Added Doxygen TODOs

src/protocols/RTTY/RTTY.cpp

@@ -452,8 +452,7 @@ size_t RTTYClient::printNumber(unsigned long n, uint8_t base) {
   return(l);
 }
 
-// TODO: improve ITA2 float print speed
-//       (characters are sent one at a time)
+/// \todo improve ITA2 float print speed (characters are sent one at a time)
 size_t RTTYClient::printFloat(double number, uint8_t digits)  {
   size_t n = 0;