update container examples in readme

README.md

@@ -51,3 +51,50 @@ completions.  By default, the manual pages and shell completions are
 put into the `cargo` target directory, but the exact location is
 unpredictable.  To write the assets to a predictable location, set the
 environment variable `ASSET_OUT_DIR` to a suitable location.
+
+## Using a Container (Docker, Podman, etc.)
+
+The command line tool `sq` can also be built using an OCI compatible image
+builder, eg. podman or docker:
+
+```shell
+$ podman build -f Containerfile -t sq .
+$ podman run --rm -i sq --help
+```
+
+You can then use sq in the container.
+
+For example searching for a certificate:
+
+```shell
+$ podman run --rm -i sq network search 653909A2F0E37C106F5FAF546C8857E0D8E8F074
+```
+
+All sq state is stored under `/sequoia` inside of the container, thus if you
+would like to persist the state between container runs you may bind mount the
+directory on the host.
+
+```shell
+$ mkdir sq-container # create a directory on the host where you will mount the working dir from the container
+$ podman run --rm -i -v $PWD/sq-container:/sequoia sq network search 653909A2F0E37C106F5FAF546C8857E0D8E8F074
+$ podman run --rm -i -v $PWD/sq-container:/sequoia sq inspect --cert 653909A2F0E37C106F5FAF546C8857E0D8E8F074
+
+```
+
+The container environment has sq manpages and bash completion configured. By
+default the container will run sq as its "entrypoint", so if you would like
+to be dropped into a shell then override the entrypoint as follows.
+
+```shell
+# Note the "-t"; Necessary for the allocation of a pseudo-TTY.
+$ podman run --rm -t -i --entrypoint bash sq
+```
+
+A current build of the container image is available from the gitlab registry.
+Rename it to `sq` locally so that it matches the above commands and for convenience.
+
+```shell
+$ podman pull registry.gitlab.com/sequoia-pgp/sequoia-sq:latest
+$ podman tag registry.gitlab.com/sequoia-pgp/sequoia-sq:latest sq
+$ podman run --rm -i sq --help
+```