Update the causal discovery notebook with examples using causal-learn (…

…#1026)

* updated a notebook with examples for causal-learn

Signed-off-by: kunwuz <514397511@qq.com>

* cleaned the output

Signed-off-by: kunwuz <514397511@qq.com>

* fixed a typo

Signed-off-by: kunwuz <514397511@qq.com>

* updated the notebook and introduced new function to load dataset

Signed-off-by: kunwuz <514397511@qq.com>

* updated some description

Signed-off-by: kunwuz <514397511@qq.com>

---------

Signed-off-by: kunwuz <514397511@qq.com>