Update migrating-from-v10-to-v11.md

Author: alex-page

documentation/guides/migrating-from-v10-to-v11.md

@@ -18,6 +18,10 @@ NodeJS version 14 is no longer supported. NodeJS 18 is recommended and 16 is the
 
 React version 16 and 17 is no longer supported. React 18 is the minimum supported version.
 
+## Webpack support
+
+Webpack version 4 is no longer supported. Webpack 5 is the minimum supported version.
+
 ## TypeScript
 
 Built types in `@shopify/polaris` have moved from `build/ts/latest` to `build/ts`.