Remove rules that lint the Markdown code itself; focus on the rendered output

[iansan5653]

After using the extension for a while, I think I should remove the unordered list style rule that enforces the use of asterisks instead of hyphens. This does make the Markdown code itself more readable with a screen reader, but it doesn't affect the rendered output and it's a lot of noise for little gain. I think I want this extension to focus on the high-impact rules so that we can maximize the 'signal-to-noise' ratio. In other words, I want to minimize lint errors to focus on the important ones.