Fix Assignment/Definition typo in Output (#21442)

See below result from running this locally:

PS C:\> $newDefinition = New-AzCosmosDBSqlRoleDefinition `
>> -ResourceGroupName $resourceGroupName `
>> -AccountName $accountName `
>> -RoleName "Quality Management Service CosmosDB Contributor" `
>> -AssignableScope "/dbs/$cosmosDatabaseName" `
>> -DataAction $builtInCosmosContributorRole.Permissions.dataActions
PS C:\> $newDefinition.GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     False    PSSqlRoleDefinitionGetResults            System.Object

Author: geologyrocks

src/CosmosDB/CosmosDB/help/New-AzCosmosDBSqlRoleDefinition.md

@@ -285,7 +285,7 @@ This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable
 ### Microsoft.Azure.Commands.CosmosDB.Models.PSSqlRoleDefinitionGetResults
 ## OUTPUTS
 
-### Microsoft.Azure.Commands.CosmosDB.Models.PSSqlRoleAssignmentGetResults
+### Microsoft.Azure.Commands.CosmosDB.Models.PSSqlRoleDefinitionGetResults
 ## NOTES
 
 ## RELATED LINKS