[docs] Update migration guide to have a section on nested classes (#27354)
[docs] Update migration guide to have a section on nested classes (#27354)


mui-org/material-ui,oliviertassinari/material-ui,rscnt/material-ui,oliviertassinari/material-ui,oliviertassinari/material-ui,rscnt/material-ui,rscnt/material-ui,mui-org/material-ui,mui-org/material-ui