docs(README): add rbuilder to used-by

README.md

@@ -116,6 +116,7 @@ cargo run -p revm --features std,serde-json,ethersdb --example generate_block_tr
 * [Hardhat](https://github.com/NomicFoundation/hardhat) is a development environment to compile, deploy, test, and debug your Ethereum software.
 * [Trin](https://github.com/ethereum/trin) is Portal Network client. An execution and consensus layer Ethereum light client written in Rust. Portal Network client's provide complete, provable, and distributed execution archival access.
 * [Simular](https://github.com/simular-fi/simular/) is a Python smart-contract API with a fast, embedded, Ethereum Virtual Machine.
+* [rbuilder](https://github.com/flashbots/rbuilder) is a state of the art Ethereum MEV-Boost block builder written in Rust and designed to work with Reth.
 * ...
 
 (If you want to add project to the list, ping me or open the PR)