docs: add marked-directive to known extensions (#3058)

docs/USING_ADVANCED.md

@@ -86,6 +86,7 @@ Marked can be extended using [custom extensions](/using_pro#extensions). This is
 |[Code JSX Renderer](https://github.com/bent10/marked-extensions/tree/main/packages/code-jsx-renderer)|[`marked-code-jsx-renderer`](https://www.npmjs.com/package/marked-code-jsx-renderer)|Render JSX code blocks using a custom renderer and components|
 |[Code Preview](https://github.com/bent10/marked-extensions/tree/main/packages/code-preview)|[`marked-code-preview`](https://www.npmjs.com/package/marked-code-preview)|Transform code blocks into code previews|
 |[Custom Heading ID](https://github.com/markedjs/marked-custom-heading-id)|[`marked-custom-heading-id`](https://www.npmjs.com/package/marked-custom-heading-id)|Specify a custom heading id in headings with the [Markdown Extended Syntax](https://www.markdownguide.org/extended-syntax/#heading-ids) `# heading {#custom-id}`|
+|[Directive](https://github.com/bent10/marked-extensions/tree/main/packages/directive)|[`marked-directive`](https://www.npmjs.com/package/marked-directive)|Supports [directives syntax](https://talk.commonmark.org/t/generic-directives-plugins-syntax/444)|
 |[Emoji](https://github.com/UziTech/marked-emoji)|[`marked-emoji`](https://www.npmjs.com/package/marked-emoji)|Add emoji support like on GitHub|
 |[Extended Tables](https://github.com/calculuschild/marked-extended-tables)|[`marked-extended-tables`](https://www.npmjs.com/package/marked-extended-tables)|Extends the standard Github-Flavored tables to support advanced features: Column Spanning, Row Spanning, Multi-row headers|
 |[Footnote](https://github.com/bent10/marked-extensions/tree/main/packages/footnote)|[`marked-footnote`](https://www.npmjs.com/package/marked-footnote)|Enables [GFM footnotes](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#footnotes)|