[docs] Improve v3 migration guide (#15527)
[docs] Improve v3 migration guide (#15527)

* Fix typo in docs

I think there was a type in the keyframes API example 🤔

Because why would you have to change animation from a regular string to a string literal, when you are not using the `${}` syntax? I might be wrong though...

* Update migration-v3.md

* Link JSS

oliviertassinari/material-ui,mbrookes/material-ui,mbrookes/material-ui,rscnt/material-ui,mui-org/material-ui,mui-org/material-ui,mbrookes/material-ui,lgollut/material-ui,callemall/material-ui,mui-org/material-ui,callemall/material-ui,oliviertassinari/material-ui,kybarg/material-ui,callemall/material-ui,callemall/material-ui,rscnt/material-ui,kybarg/material-ui,allanalexandre/material-ui,kybarg/material-ui,rscnt/material-ui,oliviertassinari/material-ui,kybarg/material-ui