Links should open in new tabs

[davidmillson]

External links in readme files should default to opening in a new tab, instead of navigating away from the Github repo (assuming that's where it's being viewed).

Solution here: https://www.codegenes.net/blog/open-link-in-new-tab-with-github-markdown-using-target-blank/

[davidmillson]

This change didn't work. May not be possible to do this in Github markdown