Fixed misspelled return keyword in Decrement method

maybe.cs

public Maybe<int> Decrement(int number) 
{
  if (number <= 0)
  {
    return Maybe<int>.None;
  }
  
  return Maybe<int>(number-1);
}


Maybe<int> test1 = Decrement(100);
test1.Match(
  some: x => Console.Writeline($"It has a value: {x}"),
  none: () => Console.Wreiteline("It has no value")
);
// output from test1 would be: "It has a value: 99"

Maybe<int> test2 = Decrement(0);
test1.Match(
  some: x => Console.Writeline($"It has a value: {x}"),
  none: () => Console.Wreiteline("It has no value")
);
// output from test2 would be: "It has no value"