Document empty IP address

[eriksjolund]

Document the somewhat surprising fact that IPAddress is empty when running podman inspect

Example

1. Run a long-running container

   $ podman run --rm --name test -d docker.io/alpine sleep inf
   c8c69b32d026275ba83e233313d5bab979b21573e79129e0db7508eb6366c7a3
   

2. Show IP address with podman inspect

   $ podman inspect test | grep IPAddress
                  "IPAddress": "",
   

3. Show IP address with podman inspect but use a Go template

   $ podman inspect --format "IP: {{.NetworkSettings.IPAddress}}" test
   IP: 
   

Step 2 and step 3 are just different ways of showing the same information.

about the system:

$ podman --version
podman version 4.9.0
$ rpm-ostree status
State: idle
Deployments:
● ostree-remote-image:fedora:docker://quay.io/fedora/fedora-coreos:rawhide
                   Digest: sha256:cb54cb7d902a599c2b334e220b1a8a9e28d09d89b685758ff044f3d33376fae6
                  Version: 40.20240202.91.0 (2024-02-02T14:14:19Z)