China approves Shenzhen-Hong Kong stock link, scraps limits

* Second link unlikely to trigger demand for mainland stocks * Scheme seen positive in longer term * Southbound usage grows on Hong Kong-Shanghai Connect * Aggregate quota limits scrapped (Adds comments from HKEx press conference) By Michelle Price HONG KONG, Aug 16 (Reuters) - In the biggest capital market reforms since last year's stock market crash, China approved the launch of a long-awaited scheme to allow stock trading between Hong Kong and Shenzhen, the world's second-busiest, and tech-he