fix doxygen

Adafruit_I2CDevice.cpp

@@ -35,6 +35,9 @@ bool Adafruit_I2CDevice::begin(bool addr_detect) {
   return true;
 }
 
+/*!
+ *    @brief  De-initialize device, turn off the Wire interface
+ */
 void Adafruit_I2CDevice::end(void) {
 #ifndef ESP8266
   // ESP8266 does not implement Wire::end()