Mentioning ssh_command for additional SSH configuration..

borgmatic/config/schema.yaml

@@ -43,7 +43,8 @@ map:
                     - type: scalar
                 desc: |
                     Paths to local or remote repositories (required). Tildes are expanded. Multiple
-                    repositories are backed up to in sequence.
+                    repositories are backed up to in sequence. See ssh_command for SSH options like
+                    identity file or port.
                 example:
                     - user@backupserver:sourcehostname.borg
             patterns: