[docs] Feedback on Toolpad Core mention in MUI templates

[prakhargupta1]

Related page

https://mui.com/material-ui/getting-started/templates/#toolpad-core-beta

Issue description

Olivier's feedback on mui/material-ui#44415

1. These redirects should be in Toolpad repository.
2. Wrong light mode image size.
   Note: I rechecked the dark and light images, and the size is same. I can't figure out what's wrong.
3. https://github.com/mui/material-ui/pull/44415/files#diff-6c8074cc0cbdc7ebecdca83a8bffea83d4b53608423228e56f0acbf9e050de80R27 to be moved under callout.

[bharatkashyap]

1. These redirects should be in Toolpad repository.

I added these redirects on the Toolpad docs website but that alone wasn't enough to make the https://mui.com level redirection work: https://mui.com/toolpad/core/templates/nextjs-dashboard still returned a 404 page.

2. Wrong light mode image size.
   Note: I rechecked the dark and light images, and the size is same. I can't figure out what's wrong.

👍🏻

3. https://github.com/mui/material-ui/pull/44415/files#diff-6c8074cc0cbdc7ebecdca83a8bffea83d4b53608423228e56f0acbf9e050de80R27 to be moved under callout.

It's already under the callout, isnt it?

[prakhargupta1]

It's already under the callout, isnt it?

Sorry, I think it was that the callout should be below: 'If you see any room for improvement, please feel free to open an issue or a pull request on GitHub.'

@oliviertassinari can you confirm?