Add TopicBench to Tools (#176)

Free open-source multi-broker MQTT explorer/monitor (Rust).

README.md

@@ -168,6 +168,7 @@ Contributions welcome! Read the [contribution guidelines](contributing.md) first
 - [RunMQTT MQTT Topic ACL Linter](https://runmqtt.com/mqtt-acl-linter) - Browser-based, local-only validator for MQTT topic-filter ACLs that checks wildcard breadth, tenant boundaries, publish/subscribe direction, placeholders, and overlapping rules. [Source and method](https://github.com/visoar/mqtt-acl-linter).
 - [SimpleMQTT](https://simplemqtt.theoi.de/) - A Slack app to send messages from Slack to MQTT brokers with slash commands.
 - [Spitfire](https://usespitfire.com/guides/mqtt-load-testing) - Self-hosted distributed load testing platform with a web UI; simulates thousands of MQTT devices (QoS 0/1/2 publish, subscribe, request-reply) alongside HTTP, Kafka and other protocols. Commercial, with a free edition.
+- [TopicBench](https://github.com/unipsycho/topicbench) - Free open-source multi-broker MQTT explorer and monitor desktop client, written in Rust.
 - [Wireshark-MQTT](https://github.com/menudoproblema/Wireshark-MQTT) - MQTT dissector for Wireshark.
 - [VSMQTT](https://github.com/rpdswtk/vsmqtt) - Simple MQTT client integrated in Visual Studio Code.
 - [MQTTX](https://github.com/emqx/MQTTX) - Cross-platform MQTT desktop client open sourced by EMQ, which supports macOS, Linux, and Windows.