sys/arduino: fix typos in documentation

sys/arduino/doc.txt

@@ -12,7 +12,7 @@
  * - starting point for beginners
  * - run your existing sketches on any non-Arduino hardware supported by RIOT
  * - makes it easy to move from Arduino to RIOT
- * - use Ardunio device drivers in RIOT
+ * - use Arduino device drivers in RIOT
  * - is fun to implement :-)
  *
  * Refer to @ref sys_arduino_api for the actual API documentation
@@ -128,7 +128,7 @@
  * @todo Implement analog outputs (PWM mapping)
  * @todo Implement analog inputs (ADC mapping)
  * @todo Implement SPI interface class
- * @todo Add support for the 'Wrie Library' (I2C)
+ * @todo Add support for the 'Wire Library' (I2C)
  * @todo Add means to include various Arduino Libraries (maybe as pkg?)
  * @todo Implement anything else that is missing...
  * @todo Adapt Arduino build script, so sketches do not have to have the file