Update docs/web-testing-library/api.mdx

Co-authored-by: Tim Deschryver <[email protected]>

Author: eps1lon

docs/web-testing-library/api.mdx

@@ -50,7 +50,7 @@ your callback again until that promise rejects. This allows you to `waitFor`
 things that must be checked asynchronously.
 
 The default `interval` is `50ms`. However, it runs your callback
-immediatelybefore starting the intervals.
+immediately before starting the intervals.
 
 The `onTimeout` callback receives the error with which `waitFor` should reject.
 You can return a more detailed error with which `waitFor` should reject. For