update README

Author: Péter Hauszknecht

README.md

@@ -189,4 +189,14 @@ it('fetchUsers', async () => {
   const nextState = store.getState();
   assert.deepEqual(nextState.users, mockUsers);
 });
-```
+```
+
+---
+
+## License
+
+[MIT](https://spdx.org/licenses/MIT)
+
+## Developed by
+
+[![JayStack logo](http://services.jaystack.com/jaystack_logo_transparent_50.png)](http://jaystack.com/)