docs: add README to agents package

Triggers split workflow to populate the new cognesy/instructor-agents repo.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Dariusz Debowczyk

packages/agents/README.md

@@ -0,0 +1,15 @@
+# Instructor Agents
+
+Agent framework for building AI agents with tools, continuation criteria, and hooks.
+
+This is a read-only split from the [Instructor PHP](https://github.com/cognesy/instructor-php) monorepo.
+
+## Installation
+
+```bash
+composer require cognesy/instructor-agents
+```
+
+## Documentation
+
+See the [Instructor PHP documentation](https://instructorphp.com) for usage details.