Extract provider-agnostic sections from provider how-to pages

[khuyentran1401]

What

Extract provider-agnostic content from docs/docs/how-tos/providers/aws.mdx into shared how-to pages that each provider page references as previous or next steps. The three sections we already know are shared:

• GitOps repository
• Secrets and credentials (provider-specific credential blocks stay in each provider page)
• First sign-in

When the next provider page lands, audit it against AWS to see if more sections are duplicated and should be extracted too.

Why

Those three sections are already provider-agnostic. Once we add a second provider how-to, the content will be duplicated across pages, creating maintenance burden and a worse reading experience. Additional shared content may surface as more providers are added.

The refactor was raised by @marcelovilla in a review thread on PR #673.

We deferred this in PR #673 because the shared structure is easier to design once at least one other provider page exists.

Trigger

Pick this up when the next provider how-to (Azure or Existing) is opened as a PR. That is when the real duplication becomes visible and the shared structure can be designed against two consumers.

Acceptance criteria

• Review both provider pages side by side and identify all duplicated sections (the three above as a starting point, plus anything else found)
• Each identified shared section lives in its own how-to page
• Each provider page links to the shared pages at the right step
• Sidebar updated to surface the shared pages
• Docusaurus build passes with no broken links

References

• PR docs: add AWS provider how-to for deploying NKP #673: docs: add AWS provider how-to for deploying NKP #673
• Reviewer's comment: docs: add AWS provider how-to for deploying NKP #673 (comment)

[andrewfulton9]

Looking at the hetzner provider PR I opened other sections that are (mostly) duplicated between the AWS and new hetzner PR are:

• Install NIC (I already largely removed this from the hetzner PR by linking to the "Get started > Install NIC" page)
• Deploy
• Verify
• Update an existing deployment
• Destroy

Note that some of the above have minor differences that may still need to mentioned in the individual Provider how to pages.

I think there should be a general deployment page that includes the above mentioned sections that points to the different providers for cluster configurations. The provider pages should include specific provider prerequisites (AWS/Hetzner account, provider permissions, provider specific secrets / credentials), cost considerations, cluster configuration, provider specific troubleshooting, ect.