removes disabled field on mcp server from the docs (#2416)

Author: dingfeli

docs/agent-format.md

@@ -76,7 +76,6 @@ Each MCP server configuration can include:
 - `args` (optional): Arguments to pass to the command
 - `env` (optional): Environment variables to set for the server
 - `timeout` (optional): Timeout for each MCP request in milliseconds (default: 120000)
-- `disabled` (optional): Whether this server should be disabled (default: false)
 
 ## Tools Field