Fix note about default extensions

See [#3043](webpack/webpack#3043 (comment)) for reference.

Author: evenfrost

content/configuration/resolve.md

@@ -142,7 +142,7 @@ which is what enables users to leave off the extension when importing:
 import File from '../path/to/file'
 ```
 
-W> Using this will **override the default array**, meaning that webpack will no longer try to resolve modules using the default extensions. For modules that are imported with their extension, e.g. `import SomeFile from "./somefile.ext"`, to be properly resolved, an empty string must be included in the array.
+W> Using this will **override the default array**, meaning that webpack will no longer try to resolve modules using the default extensions. For modules that are imported with their extension, e.g. `import SomeFile from "./somefile.ext"`, to be properly resolved, a string containing "\*" must be included in the array.
 
 
 ## `resolve.mainFields`