Backport of Tweak the ocsp_ca_certificate param docs to be more clear about what kind of cert it wants into release/1.17.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #28659 to be assessed for backporting due to the inclusion of the label backport/1.17.x.

The below text is copied from the body of the original PR.

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Description

What does this PR do?

TODO only if you're a HashiCorp employee

• [x] Backport Labels: If this PR is in the ENT repo and needs to be backported, backport
  to N, N-1, and N-2, using the backport/ent/x.x.x+ent labels. If this PR is in the CE repo, you should only backport to N, using the backport/x.x.x label, not the enterprise labels.
  • [ ] If this fixes a critical security vulnerability or severity 1 bug, it will also need to be backported to the current LTS versions of Vault. To ensure this, use all available enterprise labels.
• [ ] ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature of a public function, even if that change is in a CE file, double check that applying the patch for this PR to the ENT repo and running tests doesn't break any tests. Sometimes ENT only tests rely on public functions in CE files.
• [ ] Jira: If this change has an associated Jira, it's referenced either in the PR description, commit message, or branch name.
• [ ] RFC: If this change has an associated RFC, please link it in the description.
• [ ] ENT PR: If this change has an associated ENT PR, please link it in the description. Also, make sure the changelog is in this PR, not in your ENT PR.

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Overview of commits

• 38df9cf48837cc3b17c34642e39265621396a938