chore: comment about why not using re-export [skip ci]

Author: haoqunjiang

src/index.ts

@@ -9,6 +9,7 @@ export { default as createConfig } from './createConfig'
 export { default } from './createConfig'
 
 import { defineConfigWithVueTs } from './utilities'
+// Somehow re-export can't preserve the deprecated comment to the generated d.ts file
 /**
  * @deprecated `defineConfig` is renamed to `defineConfigWithVueTs` in 14.3.0
  */