docs: update

Author: LuisValgoi

README.md

@@ -112,8 +112,11 @@ For more info, check the [seed documentation](https://github.com/SAP/ui5-webcomp
 
 ```sh
 npx create-react-app my-app --template @ui5/webcomponents-react-seed
+npm run mock
+
 # or if you want to use yarn
 yarn create react-app my-app --template @ui5/webcomponents-react-seed
+yarn mock
 ```
 
 ### Add `@ui5/webcomponents-react` to an existing app