Update Alchemy entry on Indexers page — Stellar Data API is now live

[kaankacar]

Alchemy's Stellar Data API is live; updates the Indexers page entry from "in talks / targeted launch" to the current state, with links to the Data API and RPC provider listing. Mirrors upstream stellar#2573.

[github-actions]

🤖 Claude docs review

Verdict: READY-FOR-HUMAN-APPROVAL (one ecosystem claim needs a maintainer's confirmation — see below)

Mechanics — ✓

• docs/data/indexers/README.mdx:30 — new inline link https://www.alchemy.com/docs/reference/stellar-data-api-overview is a well-formed external URL (not a mis-used relative in-repo path); reference-style [Alchemy] link definition is untouched at docs/data/indexers/README.mdx:105.
• docs/data/indexers/README.mdx:30 — relative link ../apis/rpc/providers.mdx resolves; confirmed file exists at docs/data/apis/rpc/providers.mdx.
• Single long line matches repo convention: .prettierrc.js:7 sets proseWrap: "never" for .mdx, so this isn't a formatting violation (other bullets in the same file, e.g. line 34 and line 65, are similarly long single lines).
• No heading/frontmatter/sidebar changes, no code fences, no images, no secrets in the diff.

Technical accuracy — ✓ for verifiable claims, ⚠ one unverifiable claim

• docs/data/indexers/README.mdx:30 — the added text "Alchemy also provides Stellar RPC and appears in the RPC providers list" checks out: docs/data/apis/rpc/providers.mdx:25 lists Alchemy with Testnet ✓, Mainnet ✓, Dedicated Nodes ✓, RPC Archive ✗ — the PR text doesn't overclaim archive support, consistent with that row.
• The core claim — that Alchemy's Stellar Data API is now live (vs. the prior "in talks / targeted launch") and that it serves transfer history, account balances, and NFT holdings via JSON request bodies with opaque pageKey pagination — is an external ecosystem/product-launch fact. No mcp__raven__* tools are loaded in this session and I was not granted web-fetch access, so per the triage policy I'm stating rather than guessing: this specific launch claim is unverified by me and should be confirmed by a maintainer (or against the linked Alchemy page) before merge.
• No protocol/version, network-passphrase, RPC-vs-Horizon, SDK-import, or SEP/CAP claims are touched by this diff, so the rest of the reference-fact checklist is N/A here.

Completeness — ✓

• Diff matches its own description exactly: updates the one Alchemy bullet from "in talks / targeted launch" to current live status, plus the two promised links (Data API doc, RPC providers list). Nothing partial.
• PR description says it "Mirrors upstream Update Alchemy entry on Indexers page — Stellar Data API is now live stellar/stellar-docs#2573" — worth a maintainer glance at that upstream PR for wording parity, but this PR is self-contained and doesn't depend on it landing first.
• I was not able to run gh pr list/gh pr checks in this session (tool approval required and not granted), so I could not independently confirm there's no duplicate open PR in this fork or see live CI check detail beyond the metadata already showing mergeable: MERGEABLE / mergeStateStatus: UNSTABLE. The executor should confirm checks are green independently before acting on any label.

Non-blocking nit: none beyond the launch-claim confirmation above.