By Ayenat Mersie KIGALI (Reuters) – The 56 members of the Commonwealth made broad commitments to addressing climate change and boosting trade on Saturday as they concluded a summit aimed at shoring up the relevance of a group that evolved from the British empire. The club, which covers some 2.5 billion people or about one-third of the world’s population, presents itself as a network for cooperation with shared goals, but critics say it needs to take concrete actions and be more than a talking shop. The week-long summit in Rwanda’s capital Kigali included comments from Britain’s Prince Charles …