Fix unmount doc reference in image.rst
This pointed to the container-unmount doc page. It now points to the
expected podman-image-unmount doc page.
@@ -40,6 +40,6 @@ Image
:doc:`trust <markdown/podman-image-trust.1>` Manage container image trust policy
-:doc:`unmount <markdown/podman-unmount.1>` Unmount an image's root filesystem
+:doc:`unmount <markdown/podman-image-unmount.1>` Unmount an image's root filesystem
:doc:`untag <markdown/podman-untag.1>` Removes one or more names from a locally-stored image
