fix doc

Author: ota-meshi

docs/AST.md

@@ -423,6 +423,8 @@ interface SvelteConstTag extends Node {
 }
 ```
 
+[VariableDeclarator] is a node defined in ESTree.
+
 ### SvelteRenderTag
 
 This is the `{@render}` tag node.
@@ -431,12 +433,10 @@ This is the `{@render}` tag node.
 interface SvelteRenderTag extends Node {
   type: "SvelteRenderTag";
   callee: Identifier;
-  argument: Expression | null;
+  arguments: (Expression | SpreadElement)[];
 }
 ```
 
-[VariableDeclarator] is a node defined in ESTree.
-
 ### SvelteIfBlock
 
 This is the `{#if}` tag node. `{:else if}` is also included in this node.