feat: add plugin architecture

docs/tools/index.md

@@ -22,6 +22,13 @@ You can globally allow/deny tools via `tools.allow` / `tools.deny` in `clawdbot.
 }
 ```
 
+## Plugins + tools
+
+Plugins can register **additional tools** (and CLI commands) beyond the core set.
+See [Plugins](/plugin) for install + config, and [Skills](/tools/skills) for how
+tool usage guidance is injected into prompts. Some plugins ship their own skills
+alongside tools (for example, the voice-call plugin).
+
 ## Tool inventory
 
 ### `bash`