Fix typo in `Array#difference` document [ci skip]
@@ -129,7 +129,7 @@ class Array
# ary.difference(other_ary1, other_ary2, ...) -> new_ary
#
# Returns a new array that is a copy of the original array, removing all
- # occurences of any item that also appear in +other_ary+. The order is
+ # occurrences of any item that also appear in +other_ary+. The order is
# preserved from the original array.
#
def difference(*args)
