[Doc]: Incorrect README for python-infinity

[niebayes]

The README of the python SDK python-infinity is incorrect. The column definitions of the table my_table state that there're two columns named c1 and c2, respectively. However, the subsequent insertions requires the table having columns num, body, and vec.

[niebayes]

I'd like to fix this issue.

[JinHai-CN]

I'd like to fix this issue.

OK, thanks you.

[JinHai-CN]

Fixed by #1280