docs: add a teaser message about Coprocessor launch

docs/README.md

@@ -16,6 +16,9 @@ layout:
 ---
 
 # Welcome to fhEVM
+{% hint style="success" %}
+**[Coming soon]** Learn more about Zama's fhEVM Coprocessor. [Get notified at launch](https://www.zama.ai/fhevm-coprocessor) ↗️
+{% endhint %}
 
 ## Get started
 
@@ -64,4 +67,4 @@ Collaborate with us to advance the FHE spaces and drive innovation together.
 **Zama 5-Question Developer Survey**
 
 We want to hear from you! Take 1 minute to share your thoughts and helping us enhance our documentation and libraries. **👉** [**Click here**](https://www.zama.ai/developer-survey) to participate.
-{% endhint %}
+{% endhint %}