Tesla CEO billionaire Elon Musk tweeted an 1,800-year-old Chinese poem on Monday night asking for 'peace' – and leaving users confused about what he meant. Musk, 50, posted the poem, The Quatrain of Seven Steps, in Mandarin with the word 'Humankind' above it on both Twitter and the Chinese social media site Weibo. The ancient poem describes conflict in close relationships and is used in Chinese primary schools to teach children to get along. But Chinese social media users were bewildered by the poem, unsure of Musk's reasoning behind the post. Tesla CEO billionaire Elon Musk, 50, tweeted an ancient…