Update README.md

Author: stephanos

README.md

@@ -2,7 +2,7 @@
 
 [![release](https://img.shields.io/github/v/release/stephanos/agenttally-macos)](https://github.com/stephanos/agenttally-macos/releases/latest)
 
-`AgentTally` is a standalone macOS menu bar app for tracking AI agent usage and spend.
+`AgentTally` is a standalone macOS menu bar app for tracking AI agent spending.
 
 Right now, only Claude Code is supported. The app shows your Claude Code spend for today and the current month, and refreshes every 60s.