Fix splice mistake in day1

[asungy]

Summary

This PR addresses a minor mistake made in the "Splice method in array" section in Day 1, as well as restructures some code for clarity.

Mistake with removing all elements using splice

Originally, the Day 1 tutorial claimed that the following code would remove all items:

const numbers = [1, 2, 3, 4, 5]
console.log(numbers.splice())

While numbers.splice() does return an empty list, it does not remove any items from numbers.

This can be seen in this demo.

Printing contents of numbers

As a corollary, it would be more informative to print the actual contents of numbers rather than the return values of the methods called on numbers, especially because splice modifies the array in-place.

// print return value of splice
console.log(numbers.splice(0, 1));

// print actual contents of spliced array
numbers.splice(0, 1);
console.log(numbers);