Update CHANGELOG.md

Author: Andrzej Pijanowski

CHANGELOG.md

@@ -9,7 +9,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 
+- Environment variable `VALIDATE_QUERYABLES` to enable/disable validation of queryables in search/filter requests. When set to `true`, search requests will be validated against the defined queryables, returning an error for any unsupported fields. Defaults to `false` for backward compatibility.[#532](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/532)
+
+- Environment variable `QUERYABLES_CACHE_TTL` to configure the TTL (in seconds) for caching queryables. Default is `3600` seconds (1 hour) to balance performance and freshness of queryables data. [#532](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/532)
+
 - Added retry with back-off logic for Redis related functions. [#528](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/528)
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 - Added nanosecond precision datetime filtering that ensures nanosecond precision support in filtering by datetime. This is configured via the `USE_DATETIME_NANOS` environment variable, while maintaining microseconds compatibility for datetime precision. [#529](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/529)
 
 ### Changed