Update arduino.py

typo on line 313 corrected
        Melodies of the following lenght, can cause trouble
to 
        Melodies of the following length, can cause trouble

Author: hamsolo474

Arduino/arduino.py

@@ -310,7 +310,7 @@ def Melody(self, pin, melody, durations):
         length of melody should be of same
         length as length of duration
 
-        Melodies of the following lenght, can cause trouble
+        Melodies of the following length, can cause trouble
         when playing it multiple times.
             board.Melody(9,["C4","G3","G3","A3","G3",0,"B3","C4"],
                                                 [4,8,8,4,4,4,4,4])
@@ -614,4 +614,4 @@ def read(self, adrress):
                 return int(response)
         except:
             return 0
-                                
+