[docs] Upgrade react-select

[oliviertassinari]

Closes #12270

[lucamartini]

Why did you remove the other autocomplete demos?

[oliviertassinari]

What do you mean?

[lucamartini]

sorry I was not clear, but you added the react-select-v2 on the demo page, but in this commit you also removed the other demos:
https://material-ui.com/demos/autocomplete/
https://v1-3-0.material-ui.com/demos/autocomplete/
I was just asking if there was a reason (i.e. the other ways are not supported anymore, or ...)

[oliviertassinari]

@lucamartini Oh, damn!

[oliviertassinari]

@lucamartini Do you want to add them back? My mistake!

[lucamartini]

@oliviertassinari at my workplace we are using the downshift example, we were worried about that demo disappearance :-)
If it's not a big deal, we would appreciate that!

[oliviertassinari]

@lucamartini I have commented the markdown working on the new demo. I have forgotten to undo the diff: https://github.com/mui-org/material-ui/pull/12307/files#diff-f9250f2f92b651e998e678b0a301a98c.

Let me know if you want to submit a pull request to add the demos back :).

[bogminic]

@oliviertassinari I also think downshift example is important. Let me know if you want me to submit a weekend PR to fix this issue. Tnx!

[oliviertassinari]

@bogminic Yes, please :)

[henkvhest]

Is there a way to make the multiselect multiline? It currently looks like this when you have many selected items:

I tried multiline as a prop on the TextField component but that doesn't help :(