Update Set-MailUser.md

Added description per https://office.visualstudio.com/MAX/_workitems/edit/10026456

Author: Dean-Haas

exchange/exchange-ps/exchange/Set-MailUser.md

@@ -1569,7 +1569,8 @@ Accept wildcard characters: False
 ### -ExcludeFromAllOrgHolds
 This parameter is available only in the cloud-based service.
 
-{{ Fill ExcludeFromAllOrgHolds Description }}
+The ExcludeFromAllOrgHolds switch excludes the mail user from all organization-wide Microsoft 365 retention policies. This switch can only be used for soft-deleted mail users. You don't need to specify a value with this switch.
+When you use this switch, use the Guid, DistinguishedName or ExchangeGuid property value for the identity of the soft-deleted mail user (those are the only values that guarantee uniqueness).
 
 ```yaml
 Type: SwitchParameter