fix(markdown-navigator): partial fix for markdown flavored formats

[omaardev]

Description

A partial fix for multiple styling markdown lists

What's included?

• An specific validator for ordered and unordered nested lists without correct formats

Test Steps

• npm run start
• then navigate to markdown-flavored component
• finally see the examples

General Tests for Every PR

• npm run start still works.
• npm run lint passes.
• npm run stylelint passes.
• npm test passes and code coverage is not lower.
• npm run build still works.

Screenshots or link to StackBlitz/Plunker