Backport of Fix "auto unseal" case inconsistency into release/1.14.x

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

Backport

This PR is auto-generated from #25119 to be assessed for backporting due to the inclusion of the label backport/1.14.x.

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The person who merged in the original PR is:
@schavis
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/vault/merges: 409 Merge conflict []

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

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There was inconsistency in the capitalization of auto unseal in this doc. The initial heading had it right. It shouldn't be capitalized according to the documentation style guidance for feature capitalization. Also, high availability doesn't need to be capitalized.

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Overview of commits

• 07bfa6b

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CI Results:
All Go tests succeeded! ✅

[schavis]

Applied with manual backport #26799