Update readme to 1.8.0 release
Libpod provides a library for applications looking to use the Container Pod concept,
popularized by Kubernetes. Libpod also contains the Pod Manager tool `(Podman)`. Podman manages pods, containers, container images, and container volumes.
-* [Latest Version: 1.7.0](https://github.com/containers/libpod/releases/latest)
+* [Latest Version: 1.8.0](https://github.com/containers/libpod/releases/latest)
* [Continuous Integration:](contrib/cirrus/README.md) [![Build Status](https://api.cirrus-ci.com/github/containers/libpod.svg)](https://cirrus-ci.com/github/containers/libpod/master)
* [GoDoc: ![GoDoc](https://godoc.org/github.com/containers/libpod/libpod?status.svg)](https://godoc.org/github.com/containers/libpod/libpod)
* Automated continuous release downloads (including remote-client):
