Add cagent to the list of ACP agents (#215)

Signed-off-by: Djordje Lukic <[email protected]>

Author: rumpl

docs/overview/agents.mdx

@@ -5,6 +5,7 @@ description: "Agents implementing the Agent Client Protocol"
 
 The following agents can be used with an ACP Client:
 
+- [cagent](https://github.com/docker/cagent)
 - [Claude Code](https://docs.anthropic.com/en/docs/claude-code/overview) (via [Zed's SDK adapter](https://github.com/zed-industries/claude-code-acp))
 - [Codex CLI](https://developers.openai.com/codex/cli) (via [Zed's adapter](https://github.com/zed-industries/codex-acp))
 - [Gemini CLI](https://github.com/google-gemini/gemini-cli)