Update release notes and README for 1.9.1 release

Signed-off-by: Matthew Heon <mheon@redhat.com>

README.md

@@ -5,7 +5,7 @@
 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: 1.9.0](https://github.com/containers/libpod/releases/latest)
+* [Latest Version: 1.9.1](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):

RELEASE_NOTES.md

@@ -1,5 +1,14 @@
 # Release Notes
 
+## 1.9.1
+### Bugfixes
+- Fixed a bug where healthchecks could become nonfunctional if container log paths were manually set with `--log-path` and multiple container logs were placed in the same directory ([#5915](https://github.com/containers/libpod/issues/5915))
+- Fixed a bug where rootless Podman could, when using an older `libpod.conf`, print numerous warning messages about an invalid CGroup manager config
+- Fixed a bug where rootless Podman would sometimes fail to close the rootless user namespace when joining it ([#5873](https://github.com/containers/libpod/issues/5873))
+
+### Misc
+- Updated containers/common to v0.8.2
+
 ## 1.9.0
 ### Features
 - Experimental support has been added for `podman run --userns=auto`, which automatically allocates a unique UID and GID range for the new container's user namespace