Remove extra whitespace in nested lists

[joshjohanning]

Checklist

• I have read the contributing guidelines.
• There is no similar request on existing issues (including closed ones).
• I have read the project progress and know the current progress of the project.
• I was in the master branch of the latest code.

Is your feature request related to a problem? Please describe

When creating nested lists, there is unnecessary spacing

Markdown:

- Coffee
- Tea
    * Black tea
    * Green tea
- Milk

This also affects nested lists under numbered lists:

1. Coffee
2. Tea
    * Black tea
    * Green tea
3. Milk

Describe the solution you'd like

It should be more snug like it appears in GitHub - like so:

• Coffee
• Tea
  • Black tea
  • Green tea
• Milk

Describe alternatives you've considered

Using HTML produces same output as markdown:

<ul>
  <li>Coffee</li>
  <li>Tea
    <ul>
      <li>Black tea</li>
      <li>Green tea</li>
    </ul>
  </li>
  <li>Milk</li>
</ul>

Additional context