rename staticwebapps.config.json to staticwebapp.config.json

Author: manekinekko

includes/static-web-apps-nextjs-unsupported.md

@@ -15,7 +15,7 @@ During the preview, the following features of Static Web Apps are unsupported fo
 
 - Static Web Apps provided Authentication and Authorization.
   - Instead, you can use the Next.js [Authentication](https://nextjs.org/docs/authentication) feature.
-- The `staticwebapps.config.json` file.
+- The `staticwebapp.config.json` file.
   - Features such as custom headers and routing can be controlled using the `next.config.js` file.
 - `skip_app_build` and `skip_api_build` can't be used.
 - The maximum app size for the hybrid Next.js application is 100 MB. Use [standalone](../articles/static-web-apps/deploy-nextjs-hybrid.md#enable-standalone-feature) feature by Next.js for optimized app sizes. If this is not sufficient either, consider using Static HTML exported Next.js apps if your requirement is more than 100 MB.