Update README.md (#1865)

Summary
- Link vLLM community slack
- Point to relevant channels to join if questions

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: dsikka

README.md

@@ -22,6 +22,15 @@
    <img alt="LLM Compressor Flow" src="https://github.com/user-attachments/assets/adf07594-6487-48ae-af62-d9555046d51b" width="80%" />
 </p>
 
+---
+
+💬 Join us on the [vLLM Community Slack](https://communityinviter.com/apps/vllm-dev/join-vllm-developers-slack) and share your questions, thoughts, or ideas in:
+
+- `#sig-quantization`
+- `#llm-compressor`
+
+---
+
 ## 🚀 What's New!
 
 Big updates have landed in LLM Compressor! To get a more in-depth look, check out the [deep-dive](https://x.com/RedHat_AI/status/1937865425687093554).