Add 2.19.4 to version history

_about/version-history.md

@@ -15,6 +15,7 @@ OpenSearch version | Release highlights | Release date
 [3.2.0](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.2.0.md) | Updates Search Relevance Workbench. Makes gRPC APIs generally available. Introduces derived source, updates workload management, semantic field, and star tree functionality. Adds experimental Agentic Memory APIs and Job Scheduler APIs. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.2.0.md). | 19 August 2025
 [3.1.0](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.1.0.md) | Makes GPU acceleration for vector index builds generally available. Introduces memory-optimized search for Faiss indexes using Lucene HNSW, semantic field type for streamlined semantic search, and Search Relevance Workbench for search quality optimization. Makes star-tree indexes generally available with support for comprehensive query types. Enhances observability with ML Commons metrics integration, custom index support for OpenTelemetry data, and new PPL commands for JSON manipulation. Improves agent management with Update Agent API and persistent MCP tools. Includes security enhancements with immutable user objects and new resource sharing framework. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.1.0.md). | 24 June 2025
 [3.0.0](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.0.0.md) | Upgrades to Lucene 10 for improved indexing and vector search. Adds experimental gRPC support and pull-based ingestion from Kafka and Kinesis. Introduces GPU acceleration for vector operations and semantic sentence highlighting. Improves range query performance and hybrid search with z-score normalization. Adds plan-execute-reflect agents and native MCP protocol support for agentic workflows. Enhances security with a new Java agent replacing the Security Manager. Includes PPL query improvements with lookup, join, and subsearch commands. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.0.0.md). | 06 May 2025
+[2.19.4](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.4.md) | Fixes critical security vulnerabilities across multiple components including ML Commons, Query Insights Dashboards, and SQL. Resolves bugs in Flow Framework multi-tenancy, Security wildcard matching, and Query Insights time validation. Includes extensive CVE fixes and dependency updates across dashboards plugins. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.4.md). | 06 November 2025
 [2.19.3](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.3.md) | Improves Flow Framework with enhanced memory handling and workflow step processing. Fixes several Query Insights and Query Insights Dashboards issues. Implements security updates across multiple components. Updates infrastructure components and documentation across multiple plugins. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.3.md). | 22 July 2025 
 [2.19.2](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.2.md) |  Improves query insights with better index handling, a new verbose API parameter, and a default index template. Fixes bugs across Query Insights, Observability, Flow Framework, and Dashboards. Includes multiple CVE fixes, test enhancements, and a new PGP key for artifact verification. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.2.md). | 29 April 2025
 [2.19.1](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.1.md) |  Adds execution hint for cardinality aggregator. Includes bug fixes for ML Commons, Query Insights Dashboards, and Remote Metadata SDK. Contains maintenance updates for several components. For a full list of release highlights, see the [Release Notes](https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-2.19.1.md). | 27 February 2025