fix(markdown-to-html): use regex to match new API

Author: annieyw

tools/markdown-to-html/docs-marked-renderer.ts

@@ -64,7 +64,7 @@ export class DocsMarkdownRenderer extends Renderer {
    *   {
    *    "example": "exampleName",
    *    "file": "example-html.html",
-   *    "region": "some-region",
+   *    "region": "some-region"
    *   }
    *  ) -->`
    *  turns into
@@ -79,7 +79,7 @@ export class DocsMarkdownRenderer extends Renderer {
    */
   html(html: string) {
         html = html.replace(exampleCommentRegex, (_match: string, content: string) => {
-              if (content.startsWith('{')) {
+              if (content.match(/\{[\s\S]*\}/g)) {
                   const {example, file, region} = JSON.parse(content);
                   return `<div material-docs-example="${example}"
                                file="${file}"