Provide an option to link standard classes to MDN

[FranklinYu]

For example, if my function returns Promise<string>, I would like TypeDoc to render it as Promise<string>. MDN is almost the official documentation of JavaScript (easier to read than the standard), but user may also want to link to other sources like Node.js. I imagine the API be like

typedoc --link MDN --link nodejs-v10.x ./src/

[aciccarello]

Thanks for sharing the idea. This likely won't be added to the core project anytime soon. I believe this would be a good use case for a plugin.