docs: fix spelling and grammar (#13862)

Fixed various spelling errors and grammatical issues across multiple .mdx documentation files.

www/apps/resources/app/commerce-modules/promotion/extend/page.mdx

@@ -159,7 +159,7 @@ export default defineMiddlewares({
 })
 ```
 
-The `additional_data` parameter validation is customized using `defineMiddlewares`. In the routes middleware configuration object, the `additionalDataValidator` property accepts [Zod](https://zod.dev/) validaiton rules.
+The `additional_data` parameter validation is customized using `defineMiddlewares`. In the routes middleware configuration object, the `additionalDataValidator` property accepts [Zod](https://zod.dev/) validation rules.
 
 In the snippet above, you add a validation rule indicating that `custom_name` is a string that can be passed in the `additional_data` object.