Updated example to be compile compatible with ESP32 & README.md updates

[aefo]

Updated example to work with ESP32 setup (the constructor is different, based on conditional compilation).

Added to README.md to help discovery of this library for Microzone receiver users where it's called M-Bus (instead of SBus)

Original error message for the example running on the ESP32 was:

C:\Users\myUser\Documents\Arduino\rc_receiver_mbus\sbus_example\sbus_example.ino:29:29: error: no matching function for call to 'bfs::SbusRx::SbusRx(HardwareSerial*)'
   29 | bfs::SbusRx sbus_rx(&Serial2);
      |                             ^
In file included from C:\Users\myUser\Documents\Arduino\rc_receiver_mbus\sbus_example\sbus_example.ino:26:
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:53:3: note: candidate: 'bfs::SbusRx::SbusRx(HardwareSerial*, int8_t, int8_t, bool, bool)'
   53 |   SbusRx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
      |   ^~~~~~
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:53:3: note:   candidate expects 5 arguments, 1 provided
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:50:3: note: candidate: 'bfs::SbusRx::SbusRx(HardwareSerial*, int8_t, int8_t, bool)'
   50 |   SbusRx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
      |   ^~~~~~
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:50:3: note:   candidate expects 4 arguments, 1 provided
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:47:7: note: candidate: 'constexpr bfs::SbusRx::SbusRx(const bfs::SbusRx&)'
   47 | class SbusRx {
      |       ^~~~~~
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:47:7: note:   no known conversion for argument 1 from 'HardwareSerial*' to 'const bfs::SbusRx&'
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:47:7: note: candidate: 'constexpr bfs::SbusRx::SbusRx(bfs::SbusRx&&)'
c:\Users\myUser\Documents\Arduino\libraries\Bolder_Flight_Systems_SBUS\src/sbus.h:47:7: note:   no known conversion for argument 1 from 'HardwareSerial*' to 'bfs::SbusRx&&'

exit status 1

Compilation error: no matching function for call to 'bfs::SbusRx::SbusRx(HardwareSerial*)'