docs(libraries-and-tools.md) Add vulcan proxy and kubernetes

Both vulcan proxy (vulcand) and Google kubernetes utilize etcd as
as storage engine.
Glad to do, i mised that in the copy/paste from their docs


On Mon, Jun 16, 2014 at 8:02 PM, Jonathan Boulle <notifications@github.com>
wrote:

> In Documentation/libraries-and-tools.md:
>
> > @@ -90,3 +90,5 @@ A detailed recap of client functionalities can be found in the [clients compatib
> >  - [configdb](https://git.autistici.org/ai/configdb/tree/master) - A REST relational abstraction on top of arbitrary database backends, aimed at storing configs and inventories.
> >  - [scrz](https://github.com/scrz/scrz) - Container manager, stores configuration in etcd.
> >  - [fleet](https://github.com/coreos/fleet) - Distributed init system
> > +- [GoogleCloudPlatform/kubernetes](https://github.com/GoogleCloudPlatform/kubernetes) - Container cluster manager.
> > +- [mailgun/vulcand](https://github.com/mailgun/vulcand) - HTTP proxy that uses Etcd as a configuration backend.
>
> s/Etcd/etcd/ (uphill battle this one, but at least we can be consistent in
> our own stuff)
>
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