docs: add burnstop and claude-usage companion badges

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TkXs6iE5nbtqkAKwFQPE5E

Author: phuryn

README.md

@@ -2,6 +2,8 @@
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow?style=flat-square)](https://github.com/phuryn/pm-skills/blob/main/LICENSE)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen?style=flat-square)](https://github.com/phuryn/pm-skills/blob/main/CONTRIBUTING.md)
 [![Companion: pm-skills](https://img.shields.io/badge/companion-pm--brain-blue)](https://github.com/phuryn/pm-brain)
+[![Companion: burnstop](https://img.shields.io/badge/companion-burnstop-blue)](https://github.com/phuryn/burnstop)
+[![Companion: claude-usage](https://img.shields.io/badge/companion-claude--usage-blue)](https://github.com/phuryn/claude-usage)
 
 # PM Skills Marketplace: The AI Operating System for Better Product Decisions