docs: add discord badge in README

Author: S1M0N38

README.md

@@ -1,3 +1,12 @@
-# BalatroBench
+<div align="center">
+  <h1>BalatroBench</h1>
+  <p align="center">
+    <a href="https://discord.gg/TPn6FYgGPv">
+      <img alt="Discord" src="https://img.shields.io/badge/discord-server?style=for-the-badge&logo=discord&logoColor=%23FFFFFF&color=%235865F2"/>
+    </a>
+  </p>
+  <p><em>Benchmark LLMs' strategic performance in Balatro</em></p>
+</div>
+
+______________________________________________________________________
 
-A benchmark platform for evaluating Large Language Models' strategic performance in Balatro through intelligent tool-calling and decision-making.