Fix naming: use “iterable” instead of “iteratee”.

[Iteratee](http://okmij.org/ftp/Streams.html) is a monad that provides functional way of handling I/O,
when [iterable](http://stackoverflow.com/questions/6863182/what-is-the-difference-between-iterator-and-iterable-and-how-to-use-them) is a representation of series of elements that can be iterated over.