docs/devel: update the container based tests
This section has grown a little stale so clean-up the language and
examples for current usage:
- refer to containers at the top
- mention podman can also be used
- add podman prerequisites section
- move to using "docker-help" for online help
- mention the registry and it's purpose
- don't refer to out-of-date min-glib image
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <
20210222101455.12640-6-alex.bennee@linaro.org>