Clarification about multiple contexts on "Scaling Up with Reducer and Context" documentation page

Hi, new react docs are great. I had a question about the sample code in Scaling Up with Reducer and Context. I hope this is a reasonable way to provide feedback on a specific page. I did a quick issue search and didn't find anything related. Here is some of the sample code:

import { TasksContext, TasksDispatchContext } from './TasksContext.js';

export default function TaskApp() {
  const [tasks, dispatch] = useReducer(tasksReducer, initialTasks);
  // ...
  return (
    <TasksContext.Provider value={tasks}>
      <TasksDispatchContext.Provider value={dispatch}>
        ...
      </TasksDispatchContext.Provider>
    </TasksContext.Provider>
  );
}

It's interesting that you chose that style vs:

```js
import { TasksContext, TasksDispatchContext } from './TasksContext.js';

export default function TaskApp() {
  const [tasks, dispatch] = useReducer(tasksReducer, initialTasks);
  // ...
  return (
    <TasksContext.Provider value={{ tasks, dispatch }}>
        ...
    </TasksContext.Provider>
  );
}

If I understand correctly, the benefit of multiple contexts comes in when I've memoized a component that is a child of our contexts, and then I want to use dispatch inside that child component without subscribing to changes to tasks.

This seems either important to elaborate on in the documentation page, or if you don't want to make the page more complex, maybe it'd be simpler for everyone to just use one context? One potential problem with the sample code you've chosen to share, and without explanation, is that it suggests the use of a lot of contexts, one for every bit of data you might want to share, which can lead to overwrought code in my opinion.

从“Scaling Up with Reducer and Context”页面及其链接的示例入手，尤其关注 TaskApp 和 TasksContext.js。比较使用独立 context 和单一 context 的示例，然后确定页面需要补充哪些解释或指导，以便读者理解其中的权衡，以及该示例适用的场景。