docs: add OpenACP to messaging clients (#900)

Co-authored-by: Tiger <mac@Macs-MacBook-Pro.local>

Author: psychomafia-tiger

docs/get-started/clients.mdx

@@ -62,6 +62,7 @@ These mobile-first tools bring ACP and related coding-agent workflows to phones
 - [ACP Discord](https://github.com/broven/acp-discord) (Discord)
 - [duckdb-claude-slack](https://github.com/sidequery/duckdb-claude-slack) (Slack)
 - [Juan](https://github.com/DiscreteTom/juan) (Slack)
+- [OpenACP](https://github.com/Open-ACP/OpenACP) (Telegram, Discord, Slack) — self-hosted bridge for ACP agents; streams tool calls and responses in real time
 - [Telegram ACP Bot](https://github.com/mgaitan/telegram-acp-bot) (Telegram) — through the [`telegram-acp-bot`](https://github.com/mgaitan/telegram-acp-bot) connector
 - [Telegram-ACP](https://github.com/SuperKenVery/Telegram-ACP/) (Telegram) — Supports multi-thread chat and message streaming
 - [WeChat ACP](https://github.com/formulahendry/wechat-acp) (WeChat)