Use multi-chats on the ReadTheDocs demo

[jtpio]

Should we have this feature available on the ReadTheDocs demo too, so it's easier to test?

https://jupyter-chat--262.org.readthedocs.build/en/262/lite/lab/index.html

Originally posted by @jtpio in #262 (comment)

[brichet]

It's already the case for me, with the link above.
Can it be cached on your side (or mine) ?

[jtpio]

Ah yes it renders now:

However compared to the Binder version, it seems to be missing:

• the dropdown
• the ability to move the chat to the main area

[brichet]

However compared to the Binder version, it seems to be missing:

* the dropdown

* the ability to move the chat to the main area

Right, these widgets are added only if the getChatsList and openInMain callbacks are provided, which is not the case in the example, indeed.