External links to open in new browser window

[mklilley]

All markdown links open in the same window. This is particularly problematic for links inside of notes because clicking on a link moves you away from notes and you cannot navigate back.

[mklilley]

Links to resources to help with this:

• https://marked.js.org/using_advanced
• What would be the preferred method to add target="_blank" to links? markedjs/marked#655