More update operator
You can use other operators besides You can use other operators besides $set when updating a document. The $push operator allows you to push a
value into an array, in this case we will add a new nickname to the nicknames array. when updating a document.
The $pull operator is the opposite of $push, you can pull specific items from arrays.
The $pop operator allows you to remove the first or the last value from an array. Let's say Tom's document has a property called siblings that has the value [ 'Marie', 'Bob' , 'Kevin' , 'Alex' ].