Agent host README: rewrap the introduction

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

deploy/agent-host/README.md

@@ -1,8 +1,9 @@
 # The agent host
 
 `nisse.garrett-hall.com`, made by infra/tofu#77 as `nisse-host` and since
-renamed (architecture X1). For now it holds the knowledge vault and SilverBullet, the operator's view of it (L10,
+renamed (architecture X1). For now it holds the knowledge vault and
-M5.4). The agents' containers come later (M6.1).
+SilverBullet, the operator's view of it (L10, M5.4). The agents' containers come
+later (M6.1).
 
 ## What's here