Update Get-TransportConfig.md

Removed ExO from Identity param

Author: chrisda

exchange/exchange-ps/exchange/Get-TransportConfig.md

@@ -70,13 +70,15 @@ Accept wildcard characters: False
 ```
 
 ### -Identity
+This parameter is available only in on-premises Exchange.
+
 This parameter is reserved for internal Microsoft use.
 
 ```yaml
 Type: OrganizationIdParameter
 Parameter Sets: (All)
 Aliases:
-Applicable: Exchange Server 2010, Exchange Server 2013, Exchange Server 2016, Exchange Server 2019, Exchange Online
+Applicable: Exchange Server 2010, Exchange Server 2013, Exchange Server 2016, Exchange Server 2019
 
 Required: False
 Position: 1