[design doc]: support Analyze SQL in SQLFlow (#710)
[design doc]: support Analyze SQL in SQLFlow (#710)

* design for anlyze sql

* remove magic command in example

* update by comment

sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow