add join slack badge (#1816)

Author: samuelcolvin

README.md

@@ -15,6 +15,7 @@
   <a href="https://pypi.python.org/pypi/pydantic-ai"><img src="https://img.shields.io/pypi/v/pydantic-ai.svg" alt="PyPI"></a>
   <a href="https://github.com/pydantic/pydantic-ai"><img src="https://img.shields.io/pypi/pyversions/pydantic-ai.svg" alt="versions"></a>
   <a href="https://github.com/pydantic/pydantic-ai/blob/main/LICENSE"><img src="https://img.shields.io/github/license/pydantic/pydantic-ai.svg?v" alt="license"></a>
+  <a href="https://logfire.pydantic.dev/docs/join-slack/"><img src="https://img.shields.io/badge/Slack-Join%20Slack-4A154B?logo=slack" alt="Join Slack" /></a>
 </div>
 
 ---

docs/.partials/index-header.html

@@ -23,6 +23,9 @@
   <a href="https://github.com/pydantic/pydantic-ai/blob/main/LICENSE">
     <img src="https://img.shields.io/github/license/pydantic/pydantic-ai.svg" alt="license">
   </a>
+  <a href="https://logfire.pydantic.dev/docs/join-slack/">
+    <img src="https://img.shields.io/badge/Slack-Join%20Slack-4A154B?logo=slack" alt="Join Slack" />
+  </a>
 </p>
 
 <p class="text-emphasis">