Add streamlit_book extra 📙

[ShruAgarwal]

Adding a new extra: streamlit-book from the Coming soon ⌛ section list.

I've tried it locally and would love to know your thoughts on it. 😊

P.S.: I haven't used a pre-commit hook before, so learning on the way while contributing 😅

[ShruAgarwal]

Unfortunately, I can't manage to make the gallery work with this new add-on. Did you? How does it look like?

Well, I tried adding the chapters demo only for now. 😅 Here's how it looks 👇

[arnaudmiribel]

Closing for now. Feel free to re-open, but now the gallery has changed so this might require new tweaks.