[readme] Add moonlink to iceberg-rust users (#1418)

## What changes are included in this PR?

Add moonlink into iceberg-rust users, thanks for all the contributors
and maintainers! 😀

Author: dentiny

README.md

@@ -101,6 +101,7 @@ The Apache Iceberg community is built on the principles described in the [Apache
 
 - [Databend](https://github.com/datafuselabs/databend/): An open-source cloud data warehouse that serves as a cost-effective alternative to Snowflake.
 - [Lakekeeper](https://github.com/lakekeeper/lakekeeper/): An Apache-licensed Iceberg REST Catalog with data access controls.
+- [Moonlink](https://github.com/Mooncake-Labs/moonlink): A Rust library that enables sub-second mirroring (CDC) of Postgres tables into Iceberg.
 - [RisingWave](https://github.com/risingwavelabs/risingwave): A Postgres-compatible SQL database designed for real-time event streaming data processing, analysis, and management.
 
 ## License