fix: Add a missing slash to urls

Author: bebraw

components/navigation/navigation.jsx

@@ -125,7 +125,7 @@ export default class Navigation extends React.Component {
                         <Link
                           key={ `navigation__child-${child.title}` }
                           className={ `navigation__child ${activeMod}` }
-                          to={ `/${child.url}` }>
+                          to={ `/${child.url}/` }>
                           { child.title }
                         </Link>
                       );