Update README.md

Author: fpistm

README.md

@@ -5,7 +5,7 @@
 With an STM32 board with SD card slot availability, this library enables
 reading and writing on SD card using SD card slot of a STM32 board (NUCLEO, DISCOVERY, ...).
 
-This library follow Arduin API.
+This library follow Arduino API.
 
 For more information about it, please visit:
 http://www.arduino.cc/en/Reference/SD