docs: remove Iron Irwini from distro compatibility table

Iron reached EOL (Nov 2024) and is no longer supported.

Author: YuanYuYuan

book/src/chapters/distro_compatibility.md

@@ -13,7 +13,6 @@ ros-z supports multiple ROS 2 distributions through compile-time feature flags.
 |--------------|--------------|--------------|-------------------|---------|
 | **Kilted Kaiju** | ✅ Supported | ✅ Supported | ✅ Yes | No |
 | **Jazzy Jalisco** | ✅ Supported | ✅ Supported | ✅ Yes | **Yes** |
-| **Iron Irwini** | ✅ Supported | ✅ Supported | ✅ Yes | No |
 | **Humble Hawksbill** | ✅ Supported | ❌ **Not Supported** | ❌ Placeholder | No |
 | Rolling Ridley | ✅ Supported | ✅ Supported | ✅ Yes | No |