fix: make linkTransformer a promise

Author: jsakas

src/notion-to-md.ts

@@ -16,7 +16,7 @@ import {
 import * as md from "./utils/md";
 import { getBlockChildren } from "./utils/notion";
 
-type LinkTransformer = (text: string, href: string) => string;
+type LinkTransformer = (text: string, href: string) => Promise<string>;
 
 /**
  * Converts a Notion page to Markdown.
@@ -50,7 +50,7 @@ export class NotionToMarkdown {
     this.linkTransformer = fn;
   }
 
-  linkTransformer(text: string, href: string) {
+  async linkTransformer(text: string, href: string) {
     return md.link(text, href);
   }