Update firststeps-sync_jobs_migration.md

Make more clear how to use properly the parameters.

docs/firststeps-sync_jobs_migration.md

@@ -19,4 +19,18 @@ Sync jobs are used to copy or move existing emails from an external IMAP server
 7. Make sure to tick "Active" and click "Add".
 
 !!! info
-    Once Completed, log into the mailbox and check if all emails are imported correctly. If all goes well, All your mails shall end up in your new mailbox. And don't forget to delete or deactivate the sync job after it is used.
+    Once Completed, log into the mailbox and check if all emails are imported correctly. If all goes well, All your mails shall end up in your new mailbox. And don't forget to delete or deactivate the sync job after it is used.
+    
+!!! info
+    Username, Sync into subfolder on destination, Exclude objects (regex) and Custom parameters fields can contain spaces and special characters. Use quotes for values containing special characters!
+    
+    Examples
+    
+    ```
+    Username: "Firstname Lastname"
+    Sync into subfolder destination: "INBOX/This is a synced folder"
+    Exclude objects (regex): 'fold1|fold2|f3'
+    Custom Parameters: --addheader--resyncflags --f1f2 "Deleted Messages"=Trash --f1f2 "Sent Messages"=Sent
+    ```
+    
+    For more information how to use the parameters, see this [documentation]https://imapsync.lamiral.info/README.