Revert "Revert "[OSDOCS-14494]Prune "Introduction to ROSA"""

[mletalie]

Reverts #97858

[ocpdocs-previewbot]

🤖 Wed Aug 20 18:04:54 - Prow CI generated the docs preview:

https://97860--ocpdocs-pr.netlify.app/
https://97860--ocpdocs-pr.netlify.app/openshift-rosa-hcp/latest/rosa_architecture/about-hcp.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa-hcp/latest/rosa_architecture/rosa-architecture-models.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa-hcp/latest/rosa_planning/rosa-hcp-aws-prereqs.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa-hcp/latest/rosa_release_notes/rosa-release-notes.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa/latest/architecture/rosa-architecture-models.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa/latest/rosa_planning/rosa-hcp-aws-prereqs.html
https://97860--ocpdocs-pr.netlify.app/openshift-rosa/latest/rosa_release_notes/rosa-release-notes.html

[openshift-ci]

@mletalie: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/validate-portal	426042a	link	true	/test validate-portal

Full PR test history. Your PR dashboard.

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[openshift-merge-robot]

PR needs rebase.

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