Update Cron Job Docs

pages/03.Setup/03.Cron Jobs/docs.en.md

@@ -138,6 +138,24 @@ Use ‘--gdpr’ flag to delete data to fulfill GDPR European regulation. This w
 ```
 php /path/to/mautic/bin/console mautic:maintenance:cleanup --days-old=365 --dry-run
 ```
+### De-Duplicate Contacts
+
+This cron job will find contacts with the same unique identifiers and merge them. By default, the records are merged from oldest into newest but that can be changed with the flag --newest-into-oldest.
+
+Regardless of which record is merged into which, the latest modified record's custom field data is used (except where it is empty, Mautic will error on the side of not completely losing data). Also the latest last active date is preserved and the oldest date identified date.
+
+Contacts with conflicting unique identifiers when there is more than one unique identifier are not merged.
+
+```
+php /path/to/mautic/bin/console mautic:contacts:dedup
+```
+This command will find Contacts and merge unique values from oldest into newest.
+
+```
+php /path/to/mautic/bin/console mautic:contacts:dedup --newest-into-oldest
+```
+This command will find Contacts and merge unique values from newest into oldest.
+
 
 ### MaxMind CCPA compliance