Add newline inclusive disclaimer

[diederikvdv]

Hi, I got confused due to some ambiguity with the readline and readlines function.
I propose adding a disclaimer that the newline character is also included.

Some extra references about similar functions within Python

splitlines has the argument keeplinebreaks to make this choice for including or excluding newlines explicit. It defaults to removing the newline.
https://www.w3schools.com/python/ref_string_splitlines.asp

The documentation of readlines also doesn't state anything about including or excluding the newlines. It defaults to keeping the newline: similar to the fsspec implementation.
https://www.w3schools.com/python/ref_file_readlines.asp

[martindurant]

Thanks!