docs: remove unused onAddTask prop from AddTask component

Author: meteorqz6

src/content/learn/scaling-up-with-reducer-and-context.md

@@ -1228,7 +1228,7 @@ const initialTasks = [
 import { useState } from 'react';
 import { useTasksDispatch } from './TasksContext.js';
 
-export default function AddTask({ onAddTask }) {
+export default function AddTask() {
   const [text, setText] = useState('');
   const dispatch = useTasksDispatch();
   return (