Add JSDoc comments

[Ryuno-Ki]

Hi @zachleat,

just want to get your feedback on this before I invest too much time into it.
Would you accept JSDoc comments in your code?

This way, editors would be able to suggest Autocomplete, you could use them for typing with flow and you can render documentation for the implementation.

I can't speak for others, but I find it sometimes difficult to understand, what's going on.

Since I document my Node.js projects, I developed some opinions.
For example, using ink-docstrap for rendering more appealing JSDoc html files.

Read more about JSDoc online (old URL was usejsdoc).

[kleinfreund]

Yes, I assume that's welcome. I documented code in my contributions with JSDoc, too.

[Ryuno-Ki]

Okay, since I got a positive comment + a 👍, I added docstrings to the rest of Eleventy class.
More will follow after this one get merged in.

Would help if somebody could update the _tbd._s after a merge 😅
Wasn't completely sure, what the code is supposed to do (another positive side effect when adding documentation: it forces you to write cleaner code :-D )

[Ryuno-Ki]

@zachleat Is there something blocking this from being merged?

[zachleat]

Thanks for this @Ryuno-Ki!