Update 05-openshift-rootless-build.md

[l0rd]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

When I tried to run "Buildah Tutorial 5" last step I got the following error:

$ buildah -v /home/build/output:/output:rw -v /home/build/test-script.sh:/test-script.sh:ro build -t myimage -f Containerfile.test
unknown command "build" for "buildah"

Did you mean this?
	build-using-dockerfile

To fix it I have replaced buildah "build" command with "build-using-dockerfile".

[flouthoc]

@l0rd I think original documentation is correct following PR #3368 did a sed on /bud/build so on older version bud is applicable but on newer version build and bud both should work.

[rhatdan]

This LGTM, for now.

@l0rd you need to sign your commits.

git commit -a --amend -s
git push --force

[l0rd]

@flouthoc from the doc "The instructions have been tested on OpenShift 4.3.28 with Buildah 1.14.8" and "FROM quay.io/buildah/stable:v1.14.8" make v1.14.8 the inevitable choice for those that are following the instructions step by step (as I did).

@rhatdan commit signed

Anyway I would be happy to update the doc to use the latest stable version of buildah (v1.22.3) and OpenShift (v4.8) if that's useful.

[rhatdan]

/approve
/lgtm

[openshift-ci]

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