[CI:DOCS] DISTRO_PACKAGE.md: List the packaging changes for v4

[NO NEW TESTS NEEDED]

Co-authored-by: Ashley Cui <[email protected]>
Co-authored-by: Valentin Rothberg <[email protected]>
Signed-off-by: Lokesh Mandvekar <[email protected]>

Author: 3 people

DISTRO_PACKAGE.md

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+# Podman Packaging
+
+This document is currently written with Fedora as a reference, intended for use
+by packagers of other distros as well as package users.
+
+## Fedora Users
+Podman v4 is available as an official Fedora package on Fedora 36 and rawhide.
+This version of Podman brings with it a new container stack called
+Netavark which serves as a replacement for CNI plugins
+(containernetworking-plugins on Fedora), as well as Aardvark-dns, the
+authoritative DNS server for container records.
+
+Both Netavark and Aardvark-dns are available as official Fedora packages on
+Fedora 35 and newer versions and form the default network stack for new
+installations of Podman 4.0.
+
+On Fedora 36 and newer, fresh installations of Podman v4 will
+automatically install Aardvark-dns along with Netavark.
+
+To install Podman v4:
+
+```console
+$ sudo dnf install podman
+```
+
+To update Podman from an older version to v4:
+
+```console
+$ sudo dnf update podman
+```
+
+**NOTE:** Fedora 35 users will not be able to install Podman v4 using the default yum
+repositories and are recommended to use the COPR repo below:
+
+```console
+$ sudo dnf copr enable rhcontainerbot/podman4
+
+# install or update per your needs
+$ sudo dnf install podman
+```
+
+After installation, if you would like to migrate all your containers to use
+Netavark, you will need to set `network_backend = "netavark"` under
+the `[network]` section in your containers.conf, typically located at:
+`/usr/share/containers/containers.conf`
+
+### Testing the latest development version`
+
+If you would like to test the latest unreleased upstream code, try the
+podman-next COPR
+
+```console
+$ sudo dnf copr enable rhcontainerbot/podman-next
+
+$ sudo dnf install podman
+```
+
+**CAUTION:** The podman-next COPR provides the latest unreleased sources of Podman,
+Netavark and Aardvark-dns as rpms which would override the versions provided by
+the official packages.
+
+## Distro Packagers
+
+The Fedora packaging sources for Podman are available at the [Podman
+dist-git](https://src.fedoraproject.org/rpms/podman).
+
+The main `podman` package no longer explicitly depends on
+containernetworking-plugins. The network stack dependencies are now handled in
+the [containers-common](https://src.fedoraproject.org/rpms/containers-common)
+package which allows for a single point of dependency maintenance for Podman
+and Buildah.
+
+- containers-common
+```
+Requires: container-network-stack
+Recommends: netavark
+```
+
+- netavark
+```
+Provides: container-network-stack = 2
+```
+
+- containernetworking-plugins
+```
+Provides: container-network-stack = 1
+```
+
+This configuration ensures:
+- New installations of Podman will always install netavark by default.
+- The containernetworking-plugins package will not conflict with netavark and
+users can install them together.
+
+## Listing bundled dependencies
+If you need to list the bundled dependencies in your packaging sources, you can
+process the `go.mod` file in the upstream source.
+For example, Fedora's packaging source uses:
+
+```
+$ awk '{print "Provides: bundled(golang("$1")) = "$2}' go.mod | sort | uniq | sed -e 's/-/_/g' -e '/bundled(golang())/d' -e '/bundled(golang(go\|module\|replace\|require))/d'
+```