navigation fix

App.js

 import { Provider } from 'react-redux';
 import { createStore, applyMiddleware } from 'redux';
 
-import AvailabilityScreen from './screens/AvailabilityScreen';
+import AvailabilityScreen from './screens/main/AvailabilityScreen';
 import MailScreen from './screens/MailScreen';
 //import RegisterScreen from './screens/RegisterScreen';
 import RegisterScreen from './screens/auth/RegisterScreen';
             <Stack.Screen name = "Map" component={Map}/>
             <Stack.Screen name = "Confirm" component={Confirm}/>
             <Stack.Screen name = "Cita" component={Cita}/>
+            <Stack.Screen name = "Availability" component={AvailabilityScreen}/>
           </Stack.Navigator>
         </NavigationContainer>
       </Provider>