Add Australian programming joke to README

Added a light-hearted programming joke with an Australian twist to the README,
referencing both coding bugs and drop bears for some local flavor.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -2,6 +2,8 @@
 
 # Claude Code Action
 
+> *Why do Aussie programmers prefer dark mode? Because the light brings in drop bears and bugs, mate!* 🐨🐛
+
 A general-purpose [Claude Code](https://claude.ai/code) action for GitHub PRs and issues that can answer questions and implement code changes. This action intelligently detects when to activate based on your workflow context—whether responding to @claude mentions, issue assignments, or executing automation tasks with explicit prompts. It supports multiple authentication methods including Anthropic direct API, Amazon Bedrock, and Google Vertex AI.
 
 ## Features