docs(ocis): add 8.1 updates — vault mode, blobstore CLI, 8.0→8.1 upgrade guide

[DeepDiver1975]

Port of owncloud/docs-ocis#1286 ("docs: updates required for 8.1", by @mmattel) into the monorepo.

That PR never merged upstream, so ocis 8.1 and 8.2 shipped without this content and no version folder here carries it. Verified before porting: verify-and-inspect-blobstore.adoc, upgrading_8.0.0_8.1.0.adoc and the vault section are absent from every content/ocis/* folder.

Note

Retargeted to main. #61 (retire the upstream mirror) has merged, so modules/ is now hand-editable and this PR no longer needs a chained base. The branch was rebased onto main; the tree is byte-identical to the reviewed-and-verified version, only the parent commit changed.

Where the changes land

Per the README backport rule, a feature present since 8.1 is documented in every version that has it, while pages that describe one specific version delta are only touched in the folder whose delta they are.

Substantive content → content/ocis/8.1, 8.2 and 8.3:

Change	File
== Vault Mode service configuration (+61)	admin/pages/deployment/services/s-list/storage-users.adoc
9285-9289 storage-users (vault) port range	admin/pages/deployment/services/ports-used.adoc
new Verify and Inspect a Blobstore page (+40)	admin/pages/maintenance/commands/verify-and-inspect-blobstore.adoc
its index entry	admin/pages/maintenance/commands/commands.adoc
new partial (+31)	admin/partials/maintenance/ocis-storage-users-cli.adoc
new Upgrading from 8.0.0 to 8.1.0 guide (+107)	admin/pages/migration/upgrading_8.0.0_8.1.0.adoc
its entry in the upgrade hub	admin/pages/migration/upgrading-ocis.adoc

Version bookkeeping → content/ocis/8.1 only:

Change	File
:description: → 8.0.0 → 8.1.0 delta, and the delta bullet list	admin/pages/maintenance/commands/changed-cli.adoc
:description: → 8.0.0 → 8.1.0 delta, maintainer block → docs-stable-8.1 / 8.0.0-8.1.0	admin/pages/deployment/services/env-var-changes.adoc

Copying those two into 8.2/8.3 would make them claim to describe the 8.0→8.1 delta, which is wrong for those versions. This also avoids a collision with the companion 8.2 port, which rewrites the same changed-cli.adoc.

Dropped from the port

• antora.yml — the upstream PR retargets it from next to 8.1. antora.yml is monorepo-owned (it was never in sync_paths) and every folder already carries correct per-version values: content/ocis/8.1/antora.yml has env_var_delta_name: '8.0.0-8.1.0', service_url_component: 'docs-stable-8.1', ocis_repo_url_stable: 'stable-8.1'.

Corrected while porting

• upgrading-ocis.adoc: "There are ne breaking changes in Infinite Scale 8.1" → "no".
• Stripped the trailing space on the added ports-used.adoc row.

❓ Open review question — please confirm before this leaves draft

The vault intro sentence ends mid-word upstream and is carried over verbatim rather than guessed at:

…have their own search function, sharing options and workspaces, while public links are explicitly disallow

content/ocis/*/modules/admin/pages/deployment/services/s-list/storage-users.adoc:338. @mmattel — is the intended ending "explicitly disallowed."?

Verification

• npm run antora → exit 0, no warnings or errors mentioning the new pages, the new partial, or the new xref targets. The 28 target of xref not found: next@ocis:… errors are pre-existing in content/main/modules/ROOT/pages/ocis_release_notes.adoc, which this branch does not touch.
• npm test → 17/17 pass.
• All new pages render in all three trees; the ocis-storage-users-cli partial resolves (no Unresolved directive markers anywhere under public/ocis/8.{1,2,3}/admin).
• changed-cli.html reads 8.0.0 and 8.1.0 in 8.1 and is unchanged (7.3.0 and 8.0.0) in 8.2/8.3, as intended.
• Scope check: no antora.yml and no content/ocis/{7.3,8.0} paths in the diff.

Refs: owncloud/docs-ocis#1286.

Addresses the two upstream issues this content was written for, now migrated into this repo: #84 (owncloud/docs-ocis#1259) and #88 (owncloud/docs-ocis#1287).
Refs #44