More app-friendly event description (#6684)

* More app-friendly event description

* change origin -> owner

* checked all decl_event! and changed decriptions.

* annotated parameter names for remaining events

substrate/frame/example-offchain-worker/src/lib.rs

@@ -165,7 +165,8 @@ decl_storage! {
 decl_event!(
 	/// Events generated by the module.
 	pub enum Event<T> where AccountId = <T as frame_system::Trait>::AccountId {
-		/// Event generated when new price is accepted to contribute to the average.
+		/// Event generated when new price is accepted to contribute to the average. 
+		/// [price, who]
 		NewPrice(u32, AccountId),
 	}
 );