Update Get-RetentionPolicyTag.md

Author: markjjo

exchange/exchange-ps/exchange/policy-and-compliance-retention/Get-RetentionPolicyTag.md

@@ -131,7 +131,7 @@ Accept wildcard characters: False
 ### -Mailbox
 The Mailbox parameter specifies a mailbox to return the retention tags that are assigned to the retention policy that's applied to the specified mailbox. You can use any value that uniquely identifies the mailbox. 
 
-This parameter only returns default policy tags (DPT) and personal tags; it doesn't return retention policy tags (DPT). 
+This parameter only returns default policy tags (DPTs) and personal tags; it doesn't return retention policy tags (DPT). 
 
 ```yaml
 Type: MailboxIdParameter