Filterable is pretty straightforward, but it's the only typeclass that's missing from the documentation. I would write the description for it, but the rest was written in Charles' words. So, it'd be good for consistency to have it written by Charles.

Currently all tutorials are here: https://github.com/kowainik/co-log/tree/master/co-log/example

Proposed by @vrom911. Basically, have examples directory with different complete usage examples of co-log library. I propose to have the following examples:

• Basic example where you pass LogAction IO String as an argument and feed messages to it with <& operator
• Same example