Remove extra trailing line breaks from fenced code blocks

[remyrylan]

Right now fenced code blocks are produced with a trailing inner line break, such as:

const foo = 'bar'

This change just removes trailing inner line breaks so the output will look as expected:

const foo = 'bar'

[domchristie]

Thanks again for your contribution!

I think the content of (pre-formatted) code blocks should be left as-is, because in some cases it may be intentional or significant.

The library does not (intentionally) add trailing whitespace to code blocks (as far as I'm aware), so I am guessing the trailing whitespace is in your HTML? In which case you may need to preprocess those elements to remove the trailing whitespace.

(Sorry, I don't mean to be a naysayer!)

[remyrylan]

Dang, you're right. Sorry, I'm going in circles here figuring out where the issue is between turndown, Marked, and TypeDoc... Looks like it's either TypeDoc or Marked. I'll submit PRs over there once I figure it out.

[remyrylan]

Figured out where the outside issue was, if anyone is curious:
markedjs/marked#1266

Also made a separate PR to Marked to have it default to using language-:
markedjs/marked#1265