This PR removes the following changes:
* notebooks that were converted to markdown
* mkdocs.yml file to reference the ipython notebooks rather than the
markdown files
* Makefile install vercel reverted
* hooks for markdown-exec
* notebook conversion jinja2 templates (for converting notebooks to
markdown exec format)
* Add ast parsing to determine whether we should include result="ansi".
It's not meant to be perfect, but will hopefully catch the most common
cases. Still requires manual review.
* Ideally we could suppress output in markdown-exec in the future.
