doc: clarify escaping for ES modules
Change proposed according to https://github.com/nodejs/node/issues/41052
This should make it clear how to escape special characters like #
.
I don't know if there are any more, though.
Also, how you would call this in general?
I found it as "Javascript Escape Sequence", is this a known term?
(Also, the first link below contains a dot at the end:
https://github.com/nodejs/node/blob/HEAD/CONTRIBUTING.md.
That should probably be removed.)
Edit: Changed text slightly, so the next check should be successful.