codeMirrorRef and milkdownRef are switched in Demo code

[sytolk]

Look at the <OnlineEditor ref={milkdownRef} content={md} onChange={milkdownListener} /> its have milkdownRef
https://github.com/Saul-Mirone/milkdown/blob/main/website/component/Demo/Demo.tsx#L73

but in milkdownListener codeMirrorRef is used:
https://github.com/Saul-Mirone/milkdown/blob/main/website/component/Demo/Demo.tsx#L52

As the result:

if (!current) return;
current.update(markdown); // -> this code will never reached

but if I fix this issue executing this current.update(markdown); will loop listener for changes here:
https://github.com/Saul-Mirone/milkdown/blob/main/website/component/MilkdownEditor/editor.ts#L35

[Saul-Mirone]

It's by design. It can confirm sync will only happen by one direction. Which means if change comes from codemirror, milkdown will be synced and this sync won't trigger another sync to codemirror, to prevent a infinite loop.