Link state fix changelog entry

Link the read-only ephemeral configuration fix to PR #11146 so crate
consumers can find its implementation and tests.

Author: jvff

zebra-state/CHANGELOG.md

@@ -14,7 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `init_read_only()` now returns `StateInitError::ReadOnlyEphemeralConflict` for a config with
   `ephemeral = true`, even when the configured `cache_dir` is missing or unreadable. Previously the
   cache directory was checked first, so this configuration error surfaced as
-  `StateInitError::ReadOnlyCacheDirUnreadable`.
+  `StateInitError::ReadOnlyCacheDirUnreadable`
+  ([#11146](https://github.com/ZcashFoundation/zebra/pull/11146)).
 
 ## [12.0.1] - 2026-07-27