Update README.md

[waldyrious]

• Break up a comma splice
• Add link to https://en.wikipedia.org/wiki/Literate_programming
• Move the VS Code screenshot to be under the corresponding list item
• Use semantic line breaks to improve readability of diffs and the markdown source
• Remove two excess blank lines which make no difference in the rendered HTML output

Note: this PR was inspired by / is a follow up to #75.