Updated docs for method `set_payee` & `set_controller` (#11192)

* Updated docs for method 'set_payee'

* Updated docs for method 'set_controller'

substrate/frame/staking/src/pallet/mod.rs

@@ -1109,7 +1109,7 @@ pub mod pallet {
 
 		/// (Re-)set the payment target for a controller.
 		///
-		/// Effects will be felt at the beginning of the next era.
+		/// Effects will be felt instantly (as soon as this function is completed successfully).
 		///
 		/// The dispatch origin for this call must be _Signed_ by the controller, not the stash.
 		///
@@ -1137,7 +1137,7 @@ pub mod pallet {
 
 		/// (Re-)set the controller of a stash.
 		///
-		/// Effects will be felt at the beginning of the next era.
+		/// Effects will be felt instantly (as soon as this function is completed successfully).
 		///
 		/// The dispatch origin for this call must be _Signed_ by the stash, not the controller.
 		///