Update invalid links, and update outdated info.

[HumairAK]

This pr introduces cleaning up some invalid links, and updating existing content that's a bit outdated. I've also done a bit of minimal changes to organization. In summary:

• Remove continuous-deployment docs, some were outdated (and removed in the corresponding repo), while others are found else where and linked under the users > argocd section.
• Also re-organized the "Onboarding" section, since it's not really clear what a user can find under this section, I've split this up into:
  • Users > ArgoCD
  • Users > MOC
  • Users > General FAQ
  • What was previously Users > MOC has been renamed to Operate First Support since it links to the readme at operate-first/support and is thus more accurate
  • I renames Operators to Operations so it's more clear, and not to be confused with k8s operators
  • Added the toolbox readme to Operations > Toolbox
  • Added GIthub alerts, and incident management to Operations > SRE section.
  • Clarified the distinction between "Requesting" and "Self Servicing" onboarding/access for Clusters and ArgoCD (see Users>MOC and Users>ArgoCD
• Added kafka runbook at users>kafka>troubleshooting in the same vein as the JH runbook.

[HumairAK]

What the users section now looks like:

[HumairAK]

Operations section: You'll notice I've updated the Operations page content as well, to be more generic and not mention ODH specifically.

[HumairAK]

@tumido @durandom @4n4nd

[HumairAK]

@oindrillac updated

[sesheta]

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