Re-add missing doc that was deleted.

Signed-off-by: forestmvey <[email protected]>

Author: forestmvey

docs/dev/index.md

@@ -0,0 +1,70 @@
+
+# OpenSearch SQL/PPL Engine Development Manual
+
+## Introduction
+
++ [Architecture](intro-architecture.md): a quick overview of architecture
++ [V2 Engine](intro-v2-engine.md): introduces why we developed new V2 engine
++ Concepts
++ Quickstart
+
+---
+## Clients
+
++ **CLI**
++ **JDBC Driver**
++ **ODBC Driver**
++ **Query Workbench**
+
+---
+## Deployment
+
++ **Standalone Mode**
++ **OpenSearch Cluster**
+
+---
+## Programming Guides
+
++ **API**
++ **JavaDoc**
+
+---
+## Development Guides
+
+### Language Processing
+
++ **SQL**
+  + [Aggregate Window Function](sql-aggregate-window-function.md): aggregate window function support
++ **Piped Processing Language**
+
+### Query Processing
+
++ **Query Analyzing**
+  + [Semantic Analysis](query-semantic-analysis.md): performs semantic analysis to ensure semantic correctness
+  + [Type Conversion](query-type-conversion.md): implement implicit data type conversion
++ **Query Planning**
+  + [Logical Optimization](query-optimizier-improvement.md): improvement on logical optimizer and physical implementer
++ **Query Execution**
+  + [Query Manager](query-manager.md): query management
++ **Query Acceleration**
+  + [Automatic Acceleration](query-automatic-acceleration.md): workload based automatic query acceleration proposal
+
+### Data Sources
+
++ **OpenSearch**
+  + [Relevancy Search](opensearch-relevancy-search.md): OpenSearch relevancy search functions
+  + [Sub Queries](opensearch-nested-field-subquery.md): support sub queries on OpenSearch nested field
+  + [Pagination](opensearch-pagination.md): pagination implementation by OpenSearch scroll API
++ [Prometheus](datasource-prometheus.md): Prometheus query federation
++ **File System**
+  + [Querying S3](datasource-query-s3.md): S3 query federation proposal
+
+---
+## Other Documents
+
++ **Test Framework**
+  + [Doc Test](testing-doctest.md): makes our doc live and runnable to ensure documentation correctness
+  + [Comparison Test](testing-comparison-test.md): compares with other databases to ensure functional correctness
++ **Benchmark**
+  + [Hash Join Benchmark](testing-hash-join-benchmark.md): performance test on hash join implementation
++ **Operation Tools**