MyST and jupyter book

[ashwinvis]

Add myst and jupyter-book to the Converter section.

Short pitch

Closes #19 and #29

• Why do / don't you find this tool awesome?

MyST is great because it fixes some of the shortcomings of Markdown

• How do you use this tool in your workflow?

Yes

• What advantages / disadvantages does it have compared to {another tool}?

Does not break due to whitespace changes like rST.

Checklist

• I have read and understood the contribution guidelines.
• If the entry is a software:
  • it should be maintained (at least a commit / a release in the past 3 years),
  • it is open-source with appropriate license
• Table of contents has been updated (if a section is added / removed).
• Contents have been sorted alphabetically.