Fix: event listeners

I am pretty sure it's a mistake and `removeEventListener` should be called on unmount, instead of rebinding the event.

src/components/layout/Header.js

@@ -41,7 +41,7 @@ const Header = ({
     document.addEventListener('click', clickOutside);
     return () => {
       document.removeEventListener('keydown', keyPress);
-      document.addEventListener('click', clickOutside);
+      document.removeEventListener('click', clickOutside);
       closeMenu();
     };
   });  
@@ -135,4 +135,4 @@ const Header = ({
 Header.propTypes = propTypes;
 Header.defaultProps = defaultProps;
 
-export default Header;
+export default Header;