[DOC] When type is number,update doc

[wangxiaojing]

Oracle type	Flink SQL type
NUMBER(p, s > 0) s >= 38 or (s < 38 , p + s > 38)	STRING
--	--
NUMBER(p, s > 0) s < 38,p + s = <38	DECIMAL(p + s , s)

eg：

1. number(1,37) : s < 38 p+s =38 0.0000000000000000000000000000000000001 decimal(38,37)

2.number(2,4) decimal(2,4 ) is error ,because p must have a value between 1 and 38 (both inclusive). s must have a value between 0 and p (both inclusive).

[yuxiqian]

Thanks for your contribution! Could you please rebase it with latest master branch?

[github-actions[bot]]

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