docs: carry two modelcontextprotocol.io fixes back upstream - #1590

<!-- claude-slack-attribution -->
_Requested by **Den Delimarsky, David Soria Parra** · [Slack
thread](https://ant-mcp-oss.slack.com/archives/C0BDGKP4PC6/p1793430342149349)_

Squash-merge with this description as the commit message. The two
trailers on the last lines must stay in it, so that the next subtree
pull starts from this one.

**Before:** `docs/registry/` reflects the registry docs as of 2026-01-22
(registry commit 817e1216), plus six local edits made since. The FAQ
says servers cannot be deleted, the P-384 login command lacks the
`--algorithm` flag, the organization namespace rules are missing, and
the remote servers page says a remote URL can be used by only one server
name.

**After:** `docs/registry/` is byte-identical to
`docs/modelcontextprotocol-io` in modelcontextprotocol/registry at tag
`v1.8.9` (commit ba94f657). Seven pages change (+308/-25):
authentication, faq, github-actions, package-types, quickstart,
registry-aggregators and remote-servers.

## How

`scripts/pull-registry-docs.sh` was run against a clone of the registry,
first at `v1.8.7` and then at `v1.8.9`. The script splits
`docs/modelcontextprotocol-io` and squash-pulls the result into
`docs/registry/`. `npm run prep` passes, link check included.

The `v1.8.9` pull adds two upstream changes. Since `v1.8.8` several
server names can share one remote URL
(modelcontextprotocol/registry#1806), which replaces the sentence at
remote-servers.mdx L41. The aggregators page gains an "Efficient
synchronization" section (modelcontextprotocol/registry#1798).

A later run of the script was tested against a single squash commit that
carries these trailers. It merged cleanly and changed only
`docs/registry/`.

## Conflict resolutions

Three files conflicted in the `v1.8.7` pull. In each case upstream had
added content next to a line that a local commit had also touched, and
upstream already carried the local change, so upstream's side was taken.
The `v1.8.9` pull had no conflicts.

- `github-actions.mdx`: new troubleshooting row for the `"invalid
audience"` error.
- `package-types.mdx`: new paragraph on the `mcp-name:` token boundary,
placed before the Cargo section that both sides carry identically.
- `quickstart.mdx`: the npm account prerequisite reworded to apply to
package-based servers only.

## Local commits since January

All six are carried by upstream, so nothing needs to go upstream.

- 5abdf44 removed `.mdx` suffixes from internal links. Upstream did the
same in modelcontextprotocol/registry#1052, and no suffixed links remain
there.
- 31dae91 pointed the server.json schema link at
`draft/server.schema.json`. Upstream has it from
modelcontextprotocol/registry#884.
- 91dcd51 added the SSE deprecation note to remote-servers. It was
superseded locally by 85bbf0e.
- 85bbf0e set the final SSE deprecation wording. Upstream has the
identical sentence from modelcontextprotocol/registry#1590.
- 0d17c43 changed `PyPi` to `PyPI` in the FAQ. Upstream has it at
faq.mdx L55.
- c0b3579 added the Cargo (Rust) package type section. Upstream has the
identical section from modelcontextprotocol/registry#1207 and
modelcontextprotocol/registry#1331.

## Upstream follow-ups for the registry repo (not fixed here)

1. `authentication.mdx` contradicts itself on stale DNS records. L81
says a stale TXT record left behind "will be tried first and cause
verification to fail". L404 says the registry tries all published keys
and a different key in another record does not take precedence. The code
agrees with L404: `VerifySignatureWithKeys` in
`internal/api/handlers/v0/auth/common.go` accepts the first matching key
and fails only when none match.
2. `quickstart.mdx` L130 and L134 install `mcp-publisher` from
`releases/latest`, while `github-actions.mdx` L14-17 tells readers not
to use that URL. The three workflow examples in `github-actions.mdx`
(L35, L115, L191) pin `MCP_PUBLISHER_VERSION: v1.8.1`, behind the
`v1.8.9` tag.
3. `registry-aggregators.mdx` L78 still says a `"deleted"` status
typically indicates a moderation takedown. Since publisher-managed
deletion (modelcontextprotocol/registry#893) publishers set that status
themselves. `moderation-policy.mdx` also needs attention. Neither
passage has changed upstream.

This PR was drafted with AI assistance (Claude Code).

git-subtree-dir: docs/registry
git-subtree-split: 5d7060497a1d4535dc448dd56ec699ea03c89efd

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: David Soria Parra <167242713+dsp-ant@users.noreply.github.com>