update documentation of services and schedules modules

docs/source/module/schedules/clean_old_tasks.rst

docs/source/module/schedules/index.rst

docs/source/module/schedules/send_email_notifications.rst

docs/source/module/services/index.rst

docs/source/module/services/kentik_client.rst

docs/source/module/services/processes.rst

docs/source/module/services/sharepoint.rst