Update x-fern-retries language support - #6722

Summary

x-fern-retries: { disabled: true } lets an API owner mark an individual endpoint as non-retryable, which matters for non-idempotent operations like payments or order creation where a silent retry can double-charge a customer. Until now only the Python generator honored it; every other SDK generator parsed the extension and retried anyway, so the guarantee the docs implied only held in one language. Eight generator fixes shipped on 2026-08-20 make that guarantee real in every SDK language, and this updates the extension page, which still told readers it was Python-only.

Implements docs for:

• fix(typescript): honor x-fern-retries disabled at the endpoint level — fix(typescript): honor x-fern-retries disabled at the endpoint level fern#17438
• fix(java): honor x-fern-retries disabled at the endpoint level — fix(java): honor x-fern-retries disabled at the endpoint level fern#17437
• fix(csharp): honor x-fern-retries disabled at the endpoint level — fix(csharp): honor x-fern-retries disabled at the endpoint level fern#17436
• fix(go): honor x-fern-retries disabled at the endpoint level — fix(go): honor x-fern-retries disabled at the endpoint level fern#17440
• fix(ruby): respect endpoint-level disabled retries in ruby-v2 — fix(ruby): respect endpoint-level disabled retries in ruby-v2 fern#17439
• fix(php): honor x-fern-retries disabled at the endpoint level — fix(php): honor x-fern-retries disabled at the endpoint level fern#17433
• fix(rust): disable retries for endpoints with retries disabled — fix(rust): disable retries for endpoints with retries disabled fern#17434
• fix(swift): do not retry endpoints with retries disabled — fix(swift): do not retry endpoints with retries disabled fern#17435

Changes

fern/products/api-def/openapi/extensions/retries.mdx:

• Removed the <Callout intent="info"> claiming Python-only support; the intro now says support is across all SDK languages rather than enumerating them, which avoids a list that goes stale as generators are added.
• Closing sentence now names what the endpoint setting overrides: client-level and per-request retry settings, instead of "the SDK's user custom configuration".

Support was verified against the merged generator commits in fern-api/fern (each ships a changes/unreleased/ entry under generators/{typescript,java,csharp,go,ruby-v2,php,rust,swift}/sdk) plus the pre-existing Python support. No caveats worth documenting: the Ruby fix landed in ruby-v2, which is the generator published as fern-ruby-sdk.

No SDK changelog entry (handled separately). The Chinese copy at fern/translations/zh/... is left alone — .github/workflows/sync-translations.yml re-translates stale files nightly.

Link to Devin session: https://app.devin.ai/sessions/cda8eaf72c134dd4a1eef48f36f88330