README.containers added.

This file contains information about building and default configuration
of podman, buildah, skopeo and its components, libraries etc.

Signed-off-by: Michal Cieslakiewicz <michal.cieslakiewicz@wp.pl>

README.containers

@@ -0,0 +1,29 @@
+
+Container packages (in build order):
+
+  l/libslirp
+  l/libseccomp
+  ap/slirp4netns
+  ap/conmon
+  ap/go-md2man
+  ap/crun
+  n/cni-plugins
+  ap/fuse-overlayfs
+  ap/podman
+  ap/buildah
+  ap/skopeo
+
+System-wide configuration is stored in /etc/containers/ directory.
+
+Build notes:
+
+Tools are configured to use crun binary, not default runc.
+
+Currently gccgo in slackware-current is at version 1.12.2, which is too old
+to build recent podman, buildah and skopeo. Because of this, each of 3 build
+scripts downloads and compiles go 1.13.11 (location is /tmp/go-devel) - if
+there is already go in this directory, it is reused. Therefore, to save time
+and energy, it is advised to keep /tmp/go-devel until last of container tools
+is built.
+
+Buildah binary version matches that of podman internal buildah module.