The organiser of the annual vigil to commemorate the 1989 Tiananmen Square crackdown has called on participants to light candles across Hong Kong, after the government extended coronavirus social-distancing rules. The 31-year anniversary takes place on June 4, when measures limiting group gatherings to no more than eight people are still in force.    On June 4, 1989 Chinese troops opened fire on student-led democracy protesters, Hong Kong has held an annual vigil since 1990