Clarify status of jctools-channels

[drekbour]

The channels module looks really interesting. It's no longer in jctools-experimental but is (still) neither published itself as an artifact nor documented outside of the code. Is it ready for use?

If not then perhaps a README in each modules' home could hold a general statement of the content (for future explorers).

[nitsanw]

Thanks, we can certainly improve the README in channels. The code is somewhere between experimental and usable, kind of "alpha" state. What we need is for someone to try and use it to solve some real issues and report back, for now there was just no need to release it. You can use jetpack.io to get it IIRC.