[rhoso-gitops] Docs overhaul: diagrams, app table, cluster sizing, Secret zero

[cjeanner]

Summary

• Update diagrams — replace SVG with PNG for reliable rendering across all browsers
• Deduplicate app tables — move the full applications table (with RHOSO doc links, enabled/sync columns) to the Configuration page; keep a compact name+purpose table on the Architecture page
• Baremetal requirement — replace the cluster sizing intro with the shared cluster-sizing-template include and clarify that RHOSO requires baremetal (no cloud instances)
• Remove "Next steps" footers — they conflicted with the built-in Previous/Next navigation links
• Add warning about example overlays — note in Configuration that upstream example/ paths are reference samples only, with direct links to the GitHub directories
• Correct Secret zero workflow — rewrite bootstrap credential steps: create namespace first, inject the secret out of band, then wire up Kustomize overlay and enable openstack-secrets

Also contains these two patches from #713

• Remove sync-waves — drop application-level sync-wave docs to match the "eventually converging" pattern practice
• Automated sync & dedicated namespace — document automated sync with retry, add targetRevision stability warning, update namespace refs from openshift-gitops to rhoso-gitops-standalone

Files changed (13)

• 5 content pages (_index, cluster-sizing, configuration, getting-started, troubleshooting)
• 3 modules (rhoso-gitops-about, rhoso-gitops-architecture, rhoso-gitops-configuration, rhoso-gitops-deploying)
• 2 new PNG diagrams, 2 removed SVGs

[openshift-ci]

Hi @cjeanner. Thanks for your PR.

I'm waiting for a validatedpatterns member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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