DOC: Same description of `Returns` in `isna` and `notna`

[galipremsagar]

Location of the documentation

https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.isna.html
https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.notna.html

Documentation problem

There seems to be a typo in Returns section where both isna and notna are having this same description:

Mask of bool values for each element in DataFrame that indicates whether an element is not an NA value.

Suggested fix for documentation

I think isna doc should be corrected with:

Mask of bool values for each element in DataFrame that indicates whether an element is an NA value.

[erfannariman]

Thanks for noticing this and opening the ticket. I made a PR to fix this.