fix: missing id param in function example in code example

[matheuschimelli]

In the docs, there is an piece of code that shows the following:

export const addTodo = async (id: number, text: string) => {
  await db.insert(todo).values({
    id: id,
    text: text,
  });
};

But at in the end, in the topic: "Establish server-side functions", it was wrong, because the functions didn't provided the function param to pass the id, causing a type error in typescript.

The code now fix that error.