doc: clarify escaping for ES modules

[notroid5]

Change proposed according to #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.

[jasnell]

Suggested change

	special characters need to be replaced with escape sequences, such as `#` with `%23` and `?` with `%3F`.
	special characters must be [percent-encoded][], such as `#` with `%23` and `?` with `%3F`.

Then add a new reference at the bottom of the esm.md to:

[percent-encoded]: url.md#percent-encoding-in-urls

[richardlau]

Maybe either the bit being changed or the percent-encoding-in-urls section of url.md could point to encodeURIComponent()?

[Trott]

Maybe either the bit being changed or the percent-encoding-in-urls section of url.md could point to encodeURIComponent()?

Or https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding?

[notroid5]

I'd say the link to url.md#percent-encoding-in-urls suffices here.
The other links could then be referenced in url.md#percent-encoding-in-urls. (https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding and https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent)

[ljharb]

cc @nodejs/modules

[Trott]

FWIW, the word escape does not appear in the relevant MDN doc, so maybe "encoded" is the way to go instead of "escaped" or "replaced with escape sequences". Also, and I know this wasn't introduced in this PR, but "files containing" makes it sound we're talking about the file contents when we're talking about the URL.

Suggested change

	ES modules are resolved and cached as URLs. This means that files containing
	special characters such as `#` and `?` need to be escaped.
	ES modules are resolved and cached as URLs. This means that characters such as
	`#` and `?` need to be [percent-encoded][].

Then add to the bottom:

[percent-encoding]: https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding

[nodejs-github-bot]

Landed in 3d5a7de