hook_help() text for the CMI synch operation could use some improvement and clarification, and the documentation page to which it links needs to be written.
Background: part of the task to update the hook_help texts of the modules for Drupal 8:
- review / write the hook_help text according to help guidelines
- review if the text in aggregator_help() is up to date for Drupal 8
- test the links embedded in the text
- update/review d.o. docs at http://drupal.org/documentation/modules/config