Convert bare urls to links during page generation

[sjh26]

GitHub Markdown renders bare urls as clickable links, but this does occur in the Jekyll page generation. This is a major source of issues in the generated website, as contributors reasonably (but falsely) assume that the GitHub preview of their Markdown file represents what they will see on the final page wrt links.

[sjh26]

Possible approach: https://stackoverflow.com/questions/62400828/markdown-jekyll-auto-surround-bare-urls-with-angle-brackets