fix bad macro usage

Author: pitr-ch

lib/concurrent/edge/promises.rb

@@ -564,7 +564,7 @@ def default_executor
         @DefaultExecutor
       end
 
-      # @!macro promises.shortcut.using
+      # @!macro promises.shortcut.on
       # @return [Future]
       def chain(*args, &task)
         chain_on @DefaultExecutor, *args, &task
@@ -932,7 +932,7 @@ def exception(*args)
         end
       end
 
-      # @!macro promises.shortcut.using
+      # @!macro promises.shortcut.on
       # @return [Future]
       def then(*args, &task)
         then_on @DefaultExecutor, *args, &task
@@ -950,7 +950,7 @@ def then_on(executor, *args, &task)
         ThenPromise.new(self, @DefaultExecutor, executor, args, &task).future
       end
 
-      # @!macro promises.shortcut.using
+      # @!macro promises.shortcut.on
       # @return [Future]
       def rescue(*args, &task)
         rescue_on @DefaultExecutor, *args, &task