refactor: switch default `mode` to `typescript`; fixes #834
BREAKING CHANGE:
Users must now opt into adding `settings.jsdoc.mode` set to `"jsdoc"` if they want
normal JSDoc mode. Note that "typescript" mode does not need to imply use of TypeScript
syntax, but rather use of the TypeScript flavor within JSDoc comment blocks which holds
the advantages of working in IDEs to draw in third-party module documentation and optionally
allowing one to type check one's JavaScript code by TypeScript. There
are also tools for building docs with this flavor (e.g., typedoc).
