website/.posthtmlrc

{
  "plugins": {
    "posthtml-include": {},
    "posthtml-markdownit": {
      "markdownit": {
        "html": true
      },
      "plugins": [
        {
          "plugin": "markdown-it-anchor"
        },
        {
          "plugin": "markdown-it-table-of-contents",
          "options": {
            "containerHeaderHtml": "<h3>On this page</h3>",
            "includeLevel": [
              2,
              3
            ]
          }
        },
        {
          "plugin": "markdown-it-prism"
        }
      ]
    }
  }
}