Here are the top stories and upcoming coverage plans for Reuters text service as of 10:00 p.m. GMT/6:00 a.m. SGT. For a full schedule of news and events, go to our editorial calendar on Reuters Connect. TOP STORIES GLOBAL BRITAIN-POLITICS/ New PM Rishi Sunak pledges to lead Britain out of economic crisis LONDON, Oct 25 (Reuters) - Rishi Sunak became Britain's third prime minister in two months on Tuesday and pledged to lead the country out of a profound economic crisis and rebuild trust in politics. UKRAINE-CRISIS/ Russia tells U.N. Ukraine plans 'dirty bomb,' West dismisses allegation NEAR KHERSON FRONTLINE,...