Update long-term-backup-retention-configure.md

PowerShell example had mismatched variables.

Author: gbargsley

articles/azure-sql/managed-instance/long-term-backup-retention-configure.md

@@ -264,7 +264,7 @@ This example shows how to list the LTR policies within an instance for a single
 
 ```powershell
 # gets the current version of LTR policy for a database
-$LTRPolicies = @{
+$LTRPolicy = @{
     InstanceName = $instanceName 
     DatabaseName = $dbName 
     ResourceGroupName = $resourceGroup