Add example to docker image inspect documentation

[martinstraesser]

The docker image inspect command shows a lot useful information on a Docker image. However, I am missing an explained example on what all the entries shown in the response actually mean. The current documentation makes no statement about this. I could also not find a single reference outside Docker docs. Some information can be inferred from the OCI Image Specification, others from the Docker run reference. But not all entries are explained sufficiently.

I created this issue as generalization of issue #16315

As an example, pull the latest nginx image and execute docker image inspect nginx, you will get this output:

[
    {
        "Id": "sha256:ac8efec875ce36b619cb41f91d9db579487b9d45ed29393dc957a745b1e0024f",
        "RepoTags": [
            "nginx:1.23.2",
            "nginx:latest"
        ],
        "RepoDigests": [
            "nginx@sha256:ab589a3c466e347b1c0573be23356676df90cd7ce2dbf6ec332a5f0a8b5e59db"
        ],
        "Parent": "",
        "Comment": "",
        "Created": "2022-12-06T04:46:58.320356931Z",
        "Container": "3171a476b89e47a3d602688a3d1ada78b93cc52caf218265481d9c91ca5ebcdf",
        "ContainerConfig": {
            "Hostname": "3171a476b89e",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "80/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "NGINX_VERSION=1.23.2",
                "NJS_VERSION=0.7.7",
                "PKG_RELEASE=1~bullseye"
            ],
            "Cmd": [
                "/bin/sh",
                "-c",
                "#(nop) ",
                "CMD [\"nginx\" \"-g\" \"daemon off;\"]"
            ],
            "Image": "sha256:19d855ece39b9e1bf1a9126ed89c7931f8505a2f4e5893f3c72d9b8b310b671f",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": [
                "/docker-entrypoint.sh"
            ],
            "OnBuild": null,
            "Labels": {
                "maintainer": "NGINX Docker Maintainers <docker-maint@nginx.com>"
            },
            "StopSignal": "SIGQUIT"
        },
        "DockerVersion": "20.10.12",
        "Author": "",
        "Config": {
            "Hostname": "",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "80/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "NGINX_VERSION=1.23.2",
                "NJS_VERSION=0.7.7",
                "PKG_RELEASE=1~bullseye"
            ],
            "Cmd": [
                "nginx",
                "-g",
                "daemon off;"
            ],
            "Image": "sha256:19d855ece39b9e1bf1a9126ed89c7931f8505a2f4e5893f3c72d9b8b310b671f",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": [
                "/docker-entrypoint.sh"
            ],
            "OnBuild": null,
            "Labels": {
                "maintainer": "NGINX Docker Maintainers <docker-maint@nginx.com>"
            },
            "StopSignal": "SIGQUIT"
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 141767578,
        "VirtualSize": 141767578,
        "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/872573049e3bf097fad7dee192afe78bb2c42524eb429602ae088c453652d4b2/diff:/var/lib/docker/overlay2/b08669580851d90170f32fe614a7f1c0ce1e0045eff1c2318ab55fdc5a05c34f/diff:/var/lib/docker/overlay2/47cac3f836efd18d9110de151f0a2badeb74e804313b932a18b68a03a4faf549/diff:/var/lib/docker/overlay2/63900275913ee385755ebf0115d152dc0192c49b5c5f5a910ae2c6d0f4a35803/diff:/var/lib/docker/overlay2/42a97c895a2607143d490cc67fab2c203c5b424ec98d7644c87052abf0710b32/diff",
                "MergedDir": "/var/lib/docker/overlay2/ac6162282cab60993f833557a2ec9ae20842015ec30c5c79ad95ae99dd5dcdf1/merged",
                "UpperDir": "/var/lib/docker/overlay2/ac6162282cab60993f833557a2ec9ae20842015ec30c5c79ad95ae99dd5dcdf1/diff",
                "WorkDir": "/var/lib/docker/overlay2/ac6162282cab60993f833557a2ec9ae20842015ec30c5c79ad95ae99dd5dcdf1/work"
            },
            "Name": "overlay2"
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:b5ebffba54d3e3f7fd80435fcdc34c4a96fdb2ecab0f0a298fe08f74c2f69d29",
                "sha256:2842e5d66803d5141f310218e017d24983fa8c05936c12471ba8f87451720035",
                "sha256:f88642d922a1d9af61581afab6afa968e139763f003c047ae0a7bd3b40f00392",
                "sha256:6906edffc609cbf0ddcde6528af25a4b6c187c219af4e484363bb392849a89a2",
                "sha256:aa3739f310f5e93f7519ce69e7248fd3bba426b9e7ad730d623bda63b45e8802",
                "sha256:7b72d5d921cb3acfc32df62534c75e4dbe7a14c98297c6657ae82b78ce608669"
            ]
        },
        "Metadata": {
            "LastTagTime": "0001-01-01T00:00:00Z"
        }
    }
]

Here, as an example, it is unclear to me what exactly StdInOnce means. Others are obviously self-explaining, however, I would suggest that an exemplary interpretation on what these entries mean, would help a lot.

[docker-robott]

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