improve fn node

src/components/graph/FunctionNode.tsx

@@ -72,6 +72,9 @@ export const FunctionNode = memo(function FunctionNode({ id, data, width, height
                 <NodeFooterEdgeIndicators nodeId={id} nodeType="function">
                     {bodyValue ? `${bodyValue.length} chars` : 'none'}
                 </NodeFooterEdgeIndicators>
+                <p className="text-[10px] text-muted-foreground mt-1">
+                    In config: <code className="rounded bg-muted px-0.5">{'{{ x | '}{id}{' }}'}</code> or <code>{'{{ x | '}{id}{'(a, b, key=val) }}'}</code>. Use <code>function(num, x, y, kwargs) &#123; ... &#125;</code> — kwargs has keyword args.
+                </p>
             </BaseNodeFooter>
         </BaseNode>
     )