Docs for configuring remote MCP server

Update https://coder.com/docs/ai-coder/mcp-server to specify [server config values](https://github.com/coder/dogfood/blob/e02de8c91338e64d093ac8a43e15cac60f98656d/clusters/dogfood-v2/coder/server/configs/values.yaml#L51) needed, clients supported (e.g. Claude.ai, ChatGPT, etc) 