readme update about 5.6 not supported

Author: jdavidbakr

readme.md

@@ -8,6 +8,8 @@ This package extends Laravel's native Event class to include the ability to bloc
 
 It uses a database table to track the currently running process, and each server generates a unique key to lock the command. In order to prevent a condition where a short-running command's lock doesn't last long enough, we are implementing a minimum 10 second break between the completion of the command and its next execution time, so if a command runs every minute but takes between 50 and 59 seconds to complete, the next command will be delayed one more minute.
 
+# NOTE: Laravel 5.6 now contains a function `onOneServer()` that solves the issue that this package was built to fix. Therefore, it is recommended that you use the core function instead of this package.
+
 #### For Laravel < 5.4, please use version 1.X
 
 #### Upgrading from version 1.X