fix mdx extension glob (#2729)
fix mdx extension glob (#2729)

Co-authored-by: Roberto Huertas <d4ebcf3eea5c86fd64ba57f0d4ea00bd02755349@outlook.com>
robertohuertasm/vscode-icons,JimiC/vscode-icons,JimiC/vscode-icons,vscode-icons/vscode-icons,vscode-icons/vscode-icons