SBR docs: update sbdconfig-user-guide with Quick Start, Known Issues, etc

[maximunited]

Update SBDConfig User Guide Documentation

This PR updates the SBDConfig user guide with new sections and important improvements:

Key Changes

• Quick Start Section: Added a new quick setup guide with step-by-step instructions
• Known Issues and Workarounds: Documented two critical issues:
  • Invalid default image path (requires explicit spec.image)
  • Missing SecurityContextConstraints on OpenShift (requires manual SCC creation)
• Installation Section: Completely updated with:
  • OpenShift-first approach with OperatorHub instructions
  • Complete SCC YAML for OpenShift deployments
  • Updated standard Kubernetes installation notes
• Configuration Reference: Updated to reflect:
  • image field is now required (not optional)
  • Namespace clarification (uses metadata.namespace, not spec.namespace)
  • Status fields updated to use Kubernetes Conditions pattern
• Quick Reference: Updated sbdconfig-quick-reference.md to match user guide changes

[openshift-ci]

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[maximunited]

@mshitrit - FYI

[mshitrit]

I think this PR captures and documents well some of SBR critial issues, which requires workarounds or additional attention.
However most of them should be fixed for the next release (here is the Jira epic capturing them).

I think it would be a good idea either to have a separate PR (in case there are here issues which aren't pending fix for GA), or to wait until GA with this PR - in which case it might be closed or significantly modified.