rowCount doesn't exist on type "TextareaHeightChangeMeta"

Hello! Thank you for this great component!

I am interested in determining in which line the cursor is currently placed, and I thought I might find a solution involving rowCount. When I tried to log it, as demonstrated in [the demo](https://andarist.github.io/react-textarea-autosize/), I received this error:
`Property 'rowCount' does not exist on type 'TextareaHeightChangeMeta'.`

I though you might want to know that there seems to be a mismatch between the API and the docs.

(also, if you happen to know of any way that I can determine if the cursor is placed on the first line or the last line of the textarea, I would be very grateful to know!)