Rewrite all comments to use TomDoc

Because Biscotto was forked from [codo](https://github.com/coffeedoc/codo), all of the comments of the project itself were written in JSDoc.

This PR rewrites all the comments in Biscotto to use TomDoc notation. The docs can be generated with `bin/biscotto src/ --internal`. In a subsequent PR I'll create a workflow for updating Biscotto's gh-pages branch to host the docs for this tool.