fix typo

Co-authored-by: Sebastian Silbermann <silbermann.sebastian@gmail.com>

Author: MatanBobi

docs/react-testing-library/intro.mdx

@@ -10,7 +10,7 @@ APIs for working with React components.
 ## Installation
 
 To get started with `React Testing Library`, you'll need to install it together
-with it's peerDependency `@testing-library/dom`:
+with its peerDependency `@testing-library/dom`:
 
 ```bash npm2yarn
 npm install --save-dev @testing-library/react @testing-library/dom