[markdownit] Add documentation how to set plugin options

[simonhermann]

After searching for quite some time I finally figured out what the correct syntax is. I'd appreciate if you could add this to the readme:

markdownit: {
  use: [
    'plugin1',
    ['plugin2', {option1:  true}],
  ],
},

_{This question is available on Nuxt.js community (#c113)}

[EmmanuelBeziat]

Agreed. I was trying to solve the problem too.

[janzheng]

It still throws an error if you try something like the following, but for some reason only on subsequent hot reloads. It seems to do fine on initial load...

    use: [
      ['markdown-it-attrs', {
        leftDelimiter: '[',
        rightDelimiter: ']'
      }],

I tracked down the error to markdownit-loader/lib/core.js, and this seems to not crash:

    parser = markdown(opts.preset, opts)
    if (plugins) {
      plugins.forEach(function (plugin) {
        if (Array.isArray(plugin)) {
          // plugin[0] = resolvePlugin(plugin[0])
          // parser.use.apply(parser, plugin)
          parser.use(resolvePlugin(plugin[0]), plugin[1])
        } else {
          parser.use(resolvePlugin(plugin))
        }
      })
    }