As Waymo expands into new cities with its self-driving cars, the company plans to use the $5 billion it recently borrowed to massively increase its fleet.The company, which currently has 4,000 cars, is looking to bring its total number to 8,000 by the end of the year and grow to 20,000 by the end of next year, according to people familiar with the matter.Waymo declined to comment. The company said in a statement on its website that it raised the funds to grow internationally and in the US.Waymo,...