[docs] Improve migration v5 guide

docs/src/pages/guides/migration-v4/migration-v4.md

@@ -372,6 +372,24 @@ const classes = makeStyles(theme => ({
   />
   ```
 
+- [withMobileDialog] Remove this higher-order component. The hook API allows a simpler and more flexible solution:
+
+  ```diff
+  -import withMobileDialog from '@material-ui/core/withMobileDialog';
+  +import { useTheme, useMediaQuery } from '@material-ui/core';
+
+  function ResponsiveDialog(props) {
+  - const { fullScreen } = props;
+  + const theme = useTheme();
+  + const fullScreen = useMediaQuery(theme.breakpoints.down('sm'));
+    const [open, setOpen] = React.useState(false);
+
+  // ...
+
+  -export default withMobileDialog()(ResponsiveDialog);
+  +export default ResponsiveDialog;
+  ```
+
 ### Divider
 
 - Use border instead of background color. It prevents inconsistent height on scaled screens. For people customizing the color of the border, the change requires changing the override CSS property: