[SQL] Update SQL readme to include instructions on generating golden answer files based on Hive 0.13.1.

Author: Yin Huai <yhuai@databricks.com>

Closes #5702 from yhuai/howToGenerateGoldenFiles and squashes the following commits:

9c4a7f8 [Yin Huai] Update readme to include instructions on generating golden answer files based on Hive 0.13.1.