Add Yourkit to the readme

Adds YourKit to the readme. 

It's a nice, easy-to-use java profiler that can profile both memory and cpu in a running JVM.

If we add their logo and link to their site, they'll give us a free license.

README.md

@@ -127,3 +127,9 @@ If you have any questions, you can jump in on our [discord](https://discord.com/
 You can start by joining our [discord](https://discord.com/invite/VU53p7uQcE) and introducing yourself. Even if you don't contribute code, we always love feedback.
 
 If you want to make changes, start by reading the [`client`](./client/) and [`server`](./server/) READMEs. There you'll find instructions to start Instant locally.
+
+## YourKit
+
+We're using YourKit to help us monitor Instant. They are kindly supporting Instant and other open source projects with their [full-featured Java Profiler](https://www.yourkit.com/java/profiler/index.jsp).
+
+![yklogo](https://github.com/user-attachments/assets/64788da3-1dc4-4aa6-84cd-e051fd059fd0)