fix: typo errors (#4938)

Author: x6ax6b

docs/config/README.md

@@ -147,7 +147,7 @@ Deprecated since Vue CLI 3.3, please use [`publicPath`](#publicPath) instead.
 
   To make lint errors show up in the browser overlay, you can use `lintOnSave: 'default'`. This will force `eslint-loader` to actually emit errors. this also means lint errors will now cause the compilation to fail.
 
-  Setting it to `'errors'` will force eslint-loader to emit warnings as errors as well, which means warnings will also show up in the overlay.
+  Setting it to `'error'` will force eslint-loader to emit warnings as errors as well, which means warnings will also show up in the overlay.
 
   Alternatively, you can configure the overlay to display both warnings and errors: