llms.txt: stale OpenAPI spec registration emits a 404 (Mintlify support ticket)

Follow-up from #2237.

**This is not fixable from this repo — it needs a Mintlify support ticket.**

## Problem

`https://docs.celo.org/llms.txt` ends with:

```
## OpenAPI Specs

- [openapi](https://docs.celo.org/api-reference/openapi.json)
```

That URL returns **HTTP 404**. The same section appears in `/.well-known/llms.txt`.

Any tool consuming `llms.txt` — an AI assistant indexing the docs, the docs MCP server's consumers — sees a broken link advertised as part of Celo's documentation.

## Why it can't be fixed here

Mintlify documents three sources for this section: top-level `api.openapi` in `docs.json`, `navigation[].openapi`, and page frontmatter (`api:` / `openapi:`). **None of them exist in this repo:**

- No `api` or `openapi` key in `docs.json` (top-level keys: `$schema, theme, name, colors, contextual, background, appearance, banner, fonts, favicon, navigation, navbar, logo, redirects, footer, description`)
- No `api-reference/` directory
- Zero occurrences of the string `openapi` in any `.json`, `.mdx`, `.yml` or `.yaml` file
- No page frontmatter uses `api:` or `openapi:`

`api-reference` happens to be Mintlify's *default output directory* for a configured spec, which points at a stale server-side registration from a spec configured at some point in the past. Mintlify documents no repo-side way to clear it.

The only repo-side workaround is committing a static `llms.txt`, which permanently disables auto-generation for all 264 pages. Not worth it for one bad line.

## Ask

Open a ticket with Mintlify support asking them to clear the stale OpenAPI spec registration for project `celo`, so the `## OpenAPI Specs` section stops being emitted into `llms.txt` and `/.well-known/llms.txt`.

## Verifying the fix

```bash
curl -s https://docs.celo.org/llms.txt | grep -A2 'OpenAPI Specs'
# expect: no output
```

Read the issue and inspect docs.json to confirm that no repo-side api or openapi configuration exists. Open a Mintlify support ticket for project celo requesting removal of the stale registration, then run the provided curl and grep command against both llms.txt outputs. Done means the OpenAPI Specs section is no longer emitted.

Written by the indexing model from the issue text.