(Updates details)DUBAI, June 19 (Reuters) - Turkish participation bank Kuveyt Turk has launched a $500 million, five-year sukuk offer that will price later on Thursday, a document from lead arrangers showed.The transaction is set to a price at a spread of 340 basis points over mid-swaps, a document from lead managers said, at the tight end of final guidance of 350 bps plus or minus 10 bps given ea