SDCICD-1715: updated osde2e README, created CONTRIBUTING.md and consolidated documents #3097

Namespace: <a href="https://konflux-ui.apps.stone-prd-rh01.pg1f.p1.openshiftapps.com/ns/osde2e-cicada-tenant" rel="nofollow">osde2e-cicada-tenant
PipelineRun: <a href="https://konflux-ui.apps.stone-prd-rh01.pg1f.p1.openshiftapps.com/ns/osde2e-cicada-tenant/pipelinerun/sdn-migration-on-pull-request-2hnfb" rel="nofollow">sdn-migration-on-pull-request-2hnfb

Success

Red Hat Konflux/sdn-migration-on-pull-request has successfully validated your commit.

Status	Duration	Name
🟢 Succeeded	6 seconds	init
🟢 Succeeded	8 seconds	clone-repository
🟢 Succeeded	6 seconds	prefetch-dependencies
🟢 Succeeded	4 minutes	build-container
🟢 Succeeded	9 seconds	build-image-index
🟢 Succeeded	12 seconds	deprecated-base-image-check
🟢 Succeeded	5 seconds	apply-tags
🟢 Succeeded	30 seconds	clamav-scan
🟢 Succeeded	9 seconds	sast-snyk-check
🟢 Succeeded	7 seconds	coverity-availability-check
🟢 Succeeded	28 seconds	clair-scan
🟢 Succeeded	24 seconds	ecosystem-cert-preflight-checks
🟢 Succeeded	10 seconds	sast-shell-check
🟢 Succeeded	11 seconds	sast-unicode-check
🟢 Succeeded	6 seconds	push-dockerfile
🟢 Succeeded	9 seconds	rpms-signature-scan
🟢 Succeeded	8 seconds	show-sbom