Adds subagent install image

Author: samejr

docs/images/claude-code-subagent.png

@@ -37,6 +37,8 @@ For Claude Code users, we provide a subagent called `trigger-dev-expert` that's
 
 The subagent is available as an option when running the rules installation command. Select "Claude Code" as your client and choose to include the subagent when prompted.
 
+![Claude Code subagent installation](/images/claude-code-subagent.png)
+
 ### Usage
 
 Activate the subagent in your prompts by requesting it explicitly: