Add 2.2.1 release notes.
Add 2.2.1 release notes.

ashikahmad/SlideMenuControllerSwift,m1ksoftware/SlideMenuControllerSwift,Negativchik/SlideMenuControllerSwift,m1ksoftware/SlideMenuControllerSwift,dekatotoro/SlideMenuControllerSwift,ashikahmad/SlideMenuControllerSwift,Negativchik/SlideMenuControllerSwift,dekatotoro/SlideMenuControllerSwift