Improve Markdown renderer in DocViewer

[jviotti]

Seems like it can't handle things such as:

• A language after the triple back ticks
• Back ticks in titles
• Markdown tables
• Images

We have the data correctly represented as JSONML, so we probably just need a better JSONML to markdown (or HTML) module.

Some examples:

[dimitrisnl]

Seems like this is a limitation by the library evilstreak/markdown-js#41

They don't support this syntax, and the project is un unmaintained.

Needs to find a working alternative that hopefully has some jsonml helpers too.

[dimitrisnl]

@jviotti Can you remind me how to generate/update meta.json?

The jsonML object has parsed the table as a string

              [
                "para",
                "| Arguments | Description | Optional? | Default |\n|-----------|-------------|-----------|---------|\n| ",
                [
                  "inlinecode",
                  "[meta.json]"
                ],
                " | Path to ",
                [
                  "inlinecode",
                  "meta.json"
                ],
                " | Y | ",
                [
                  "inlinecode",
                  "$PWD/meta.json"
                ],
                " |"
              ],

[jviotti]

@dimitrisnl we need to fix it here: https://github.com/balena-io/landr/blob/master/scripts/scrutinizer-stub.js

[dimitrisnl]

Should be addressed by this PR #264