Update README.md

Author: icsaba

README.md

@@ -120,10 +120,10 @@ Add some test and document what you've done. That's it :D
 
 ### Start
 
-You can try out ur changes with the command `yarn start:app:ts`
+You can try out ur changes with the command `yarn start:app:ts` or you can test how it works with js either `yarn start:app:js`. Before runninf the JS app, do not forget to create a new version locally with `yarn build && yarn pack` command.
 
 ### Test
 
 It uses `vitest` and `jsdom` for now.
 
-`yarn test:unit`
+`yarn test:unit`