Add an example of embedding indexes inside a parquet file

datafusion-examples/README.md

@@ -65,6 +65,7 @@ cargo run --example dataframe
 - [`flight_sql_server.rs`](examples/flight/flight_sql_server.rs): Run DataFusion as a standalone process and execute SQL queries from JDBC clients
 - [`function_factory.rs`](examples/function_factory.rs): Register `CREATE FUNCTION` handler to implement SQL macros
 - [`optimizer_rule.rs`](examples/optimizer_rule.rs): Use a custom OptimizerRule to replace certain predicates
+- [`parquet_embedded_index.rs`](examples/parquet_embedded_index.rs): Store a custom index inside a Parquet file and use it to speed up queries
 - [`parquet_encrypted.rs`](examples/parquet_encrypted.rs): Read and write encrypted Parquet files using DataFusion
 - [`parquet_index.rs`](examples/parquet_index.rs): Create an secondary index over several parquet files and use it to speed up queries
 - [`parquet_exec_visitor.rs`](examples/parquet_exec_visitor.rs): Extract statistics by visiting an ExecutionPlan after execution