Add Synthetic Data Generation & Features to OSB Documentation

_benchmark/features/index.md

@@ -0,0 +1,20 @@
+---
+layout: default
+title: Features
+nav_order: 30
+has_children: true
+has_toc: false
+redirect_from:
+  - /benchmark/features/
+  - /benchmark/features/index/
+more_cards:
+  - heading: "Synthetic Data Generation"
+    description: "Generate synthetic data for benchmarking"
+    link: "/benchmark/features/synthetic-data-generation/"
+---
+
+# Features
+
+On top of general benchmarking, OpenSearch Benchmark comes with other features. See the following sections for more information on each.
+
+{% include cards.html cards=page.more_cards %}