Add Cline to agents list in documentation (#450)

See: https://cline.bot/blog/announcing-cline-cli-2-0

Author: jinnovation

docs/get-started/agents.mdx

@@ -9,6 +9,7 @@ The following agents can be used with an ACP Client:
 - [Augment Code](https://docs.augmentcode.com/cli/acp)
 - [Blackbox AI](https://docs.blackbox.ai/features/blackbox-cli/introduction)
 - [Claude Code](https://docs.anthropic.com/en/docs/claude-code/overview) (via [Zed's SDK adapter](https://github.com/zed-industries/claude-code-acp))
+- [Cline](https://cline.bot/)
 - [Codex CLI](https://developers.openai.com/codex/cli) (via [Zed's adapter](https://github.com/zed-industries/codex-acp))
 - [Code Assistant](https://github.com/stippi/code-assistant?tab=readme-ov-file#configuration)
 - [Docker's cagent](https://github.com/docker/cagent)