docs: Note about TypeScript and jest setup files (#129)

Author: dariye

README.md

@@ -97,6 +97,8 @@ Import `@testing-library/jest-dom/extend-expect` once (for instance in your
 import '@testing-library/jest-dom/extend-expect'
 ```
 
+> Note: If you're using TypeScript, make sure your setup file is a `.ts` and not a `.js` to include the necessary types.
+
 Alternatively, you can selectively import only the matchers you intend to use,
 and extend jest's `expect` yourself:
 
@@ -106,9 +108,7 @@ import {toBeInTheDocument, toHaveClass} from '@testing-library/jest-dom'
 expect.extend({toBeInTheDocument, toHaveClass})
 ```
 
-> Note: when using TypeScript, this way of importing matchers won't provide the
-> necessary type definitions. More on this
-> [here](https://github.com/testing-library/jest-dom/pull/11#issuecomment-387817459).
+> Note: when using TypeScript, this way of importing matchers won't provide the necessary type definitions. More on this [here](https://github.com/testing-library/jest-dom/pull/11#issuecomment-387817459).
 
 ## Custom matchers