notifications.md

+# Notifications
+
+https://developer.apple.com/reference/foundation/nsnotificationcenter
+
+
+## You should do the following:
+1. Create a branch from develop called feature/notifications
+2. Add “Randomize order” button to `OrganizationInfoViewController`. It should randomize the order of employees in an organization.
+3. Declare `kEmployeesOrderHasChanged` string constant.
+4. Implement a logic of reloading table view on `MainViewController` after randomizing order in `OrganizationViewController` with the help of `NSNotificationCenter`.
+5. Create a pull request from your branch to develop.
+
+
+## You should be able to answer the following questions:
+* What is `NSNotificationCenter`?
+* What is the difference between delegation and notifications patterns?
+* How to unsubscribe from notifications? How and when should it be used? Is it mandatory?