Add Callstack reference (#58)

Author: michalchudziak

README.md

@@ -83,6 +83,8 @@ ReactNativeBrownfield.popToNative(true);
 
 React Native Brownfield is an open source project and will always remain free to use. If you think it's cool, please star it 🌟. [Callstack](https://callstack.com) is a group of React and React Native geeks, contact us at [[email protected]](mailto:[email protected]) if you need any help with these or just want to say hi!
 
+Like the project? ⚛️ [Join the team](https://callstack.com/careers/?utm_campaign=Senior_RN&utm_source=github&utm_medium=readme) who does amazing stuff for clients and drives React Native Open Source! 🔥
+
 ## Contributors
 
 Thanks goes to these wonderful people ([emoji key](https://github.com/kentcdodds/all-contributors#emoji-key)):