[docs] Official URL

[oliviertassinari]

In case we migrate to a different hosting solution, like https://railway.app/. It also better communicates that MUI is dog flooding. Noticed with @prakhargupta1 in a meeting.

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The content on the page doesn't make a lot of sense to me:

• I personally never use the "No shell" layout anymore, it's too much of a pain when you want to browse all the apps you have to not have the sidenav. Instead, I use ?toolpad-display=standalone, much better.
• I think https://mui.com/toolpad/how-to-guides/embed-pages/ should cross-link back to https://mui.com/toolpad/concepts/display-mode/