Add CrossDB (embedded RDBMS) (fffaraz#1586)

Author: toge

README.md

@@ -416,6 +416,7 @@ A curated list of awesome C++ (or C) frameworks, libraries, resources, and shiny
 *Database Libraries, SQL Servers, ODBC Drivers, and Tools*
 
 * [ClickHouse](https://github.com/ClickHouse/clickhouse-cpp) - C++ client for ClickHouse DBMS. [Apache2]
+* [CrossDB](https://github.com/crossdb-org/crossdb) - Ultra High-performance Lightweight Embedded and Server OLTP RDBMS. [MPL-2.0] [website](https://crossdb.org/)
 * [DuckDB](https://duckdb.org/) - in-process SQL OLAP Database Management System. [MIT]
 * [hiberlite](https://github.com/paulftw/hiberlite) - C++ Object-relational mapping for sqlite3. [BSD]
 * [Hiredis](https://github.com/redis/hiredis) - A minimalistic C client library for the Redis database. [BSD]