bufio: ReadLine doc comment references function by wrong name

[jangler]

https://github.com/golang/go/blob/master/src/bufio/bufio.go#L340-L341

The comment references "ReadBytes('\n')", when the relevant function is actually called "ReadSlice".

[jangler]

Nevermind. I see that "ReadBytes" is also a similar function, and is probably the better one to use in this case. Oops.