[harp] Unsafe rendering of Markdown files

I would like to report Cross Site Scripting vulnerablity in harp module It allows to execute arbitrary JavaScript due to unsafe rendering of markdown files. Similar to [#404126](https://hackerone.com/reports/404126)

var TerraformError = require("../../error").TerraformError
var marked = require("marked").setOptions({
  langPrefix: 'language-',
  headerPrefix: '',
  gfm: true,
  tables: true,
})
var renderer = new marked.Renderer()
...