fix the warning

Author: siriwatknp

packages/mui-material/src/styles/ThemeProviderWithVars.test.js

@@ -384,7 +384,7 @@ describe('[Material UI] ThemeProviderWithVars', () => {
     expect(() => {
       fireEvent.click(screen.getByText('Dark'));
     }).toErrorDev([
-      'MUI: The `setMode` function has no effect if `colorSchemeSelector` is not configured.\nPlease set `cssVariables.colorSchemeSelector` to `"class"` or `"data"`.\nTo learn more, visit https://mui.com/material-ui/customization/css-theme-variables/configuration/#toggling-dark-mode-manually',
+      'MUI: The `setMode` function has no effect if `colorSchemeSelector` is not configured.\nPlease create a theme with `createTheme({ cssVariables: { colorSchemeSelector: "class" | "data" } })`.\nTo learn more, visit https://mui.com/material-ui/customization/css-theme-variables/configuration/#toggling-dark-mode-manually',
     ]);
   });
 });

packages/mui-system/src/cssVars/createCssVarsProvider.js

@@ -250,7 +250,7 @@ export default function createCssVarsProvider(options) {
                   console.error(
                     [
                       'MUI: The `setMode` function has no effect if `colorSchemeSelector` is not configured.',
-                      'Please set `cssVariables.colorSchemeSelector` to `"class"` or `"data"`.',
+                      'Please create a theme with `createTheme({ cssVariables: { colorSchemeSelector: "class" | "data" } })`.',
                       'To learn more, visit https://mui.com/material-ui/customization/css-theme-variables/configuration/#toggling-dark-mode-manually',
                     ].join('\n'),
                   );