Correct an error in Array#at() method documentation
@@ -137,7 +137,7 @@ func builtinArrayInstanceMethods() []*BuiltinMethodObject {
},
{
// Retrieves an object in an array using the index argument.
- // It raises an error if index out of range.
+ // The index is 0-based; nil is returned when trying to access the index out of bounds.
//
// ```ruby
// a = [1, 2, 3]
