Fixing typo (#222)

Author: glitchassassin

exercises/README.mdx

@@ -9,7 +9,7 @@ working on in this workshop.
 We're going to cover a lot of ground and a handful of components that need to be
 enhanced for the features our users are looking for. You'll be building things
 using React hooks like `useReducer`, `use`, `useLayoutEffect`,
-`useSyncExternalStore`, and more. You'll even ben building your own custom
+`useSyncExternalStore`, and more. You'll even be building your own custom
 hooks!
 
 In addition to advanced hooks, we'll also be covering a couple advanced use