TAJO-1062: Update TSQL documentation

TAJO-1062: Update TSQL documentation
I think that the original title is better because command-line interface is too general to be title. ```bin/tajo``` and ```bin/tajo-dump``` are also command line tools.

If you thought it due to the filename ```cli.rst```, how do you think about renaming ```cli.rst``` to ```tsql.rst```?