docs: update changeset to mention beforeRequest locale passthrough

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jorgemoya

.changeset/locale-param-client.md

@@ -2,4 +2,4 @@
 "@bigcommerce/catalyst-client": minor
 ---
 
-Add optional `locale` parameter to `client.fetch()` and update `getChannelId` callback signature to `(defaultChannelId: string, locale?: string)`. This allows locale to be passed explicitly rather than resolved from headers, which is required for cached contexts where `headers()` is unavailable.
+Add optional `locale` parameter to `client.fetch()` and update `getChannelId` callback signature to `(defaultChannelId: string, locale?: string)`. Pass `locale` through to the `beforeRequest` callback as a second argument so it can set `Accept-Language` correctly inside cached contexts where `getLocale()` is unavailable.