It's one of his hedge fund's top holdings.Investors follow hedge fund managers because billionaires who manage money for other rich people are an obvious source of investing inspiration.Well-known billionaire Bill Ackman leads Pershing Square Capital, which manages $18.6 billion in assets. He's a big fan of Chipotle Mexican Grill (CMG 0.19%), and it's not hard to see why. Chipotle is a no-brainer stock to own that regularly cranks out higher sales and profits, and it has created incredible shareholder wealt ...