doc: adding note regarding http.get options

[raphaelokon]

This addresses #12092. Adds a note to doc/api/http.md that clarifies that options
doesn't include the prototype.

Checklist

• documentation is changed or added
• commit message follows [commit guidelines][]

Affected core subsystem(s)

doc

[jasnell]

Couple of style nits:

1. Please wrap at 80 chars
2. s/Note:/*Note*:/
3. Rewording to something like the following is likely sufficient:

*Note*: The `options` object's "own" properties are copied when passed.

The fact that it uses util._extend() is an internal implementation detail that should not be worth documenting and could change at any point in the future)

[Trott]

I'd like to avoid scare quotes in our docs if possible. Maybe this?:

*Note*: Properties inherited from the `options` object prototype chain are ignored.

Might it be better as part of the explanation of options and not a special note at the bottom?

  * `options` {Object | string} Accepts the same `options` as
  [`http.request()`][], with the `method` always set to `GET`.
  Properties that are inherited from the prototype are ignored.

Also: Should this note be added to all relevant functions and not just .get()?

@nodejs/documentation

[raphaelokon]

Aww sorry.
@jasnell You are right.

@Trott I was thinking adding it to all affected options occurrences later on.
I also like the idea to attach it directly to the explanation of options. If we can agree I will rebase and push again.

[Trott]

Works for me.

[raphaelokon]

Okay – added the changes.

[Trott]

LGTM.

[raphaelokon]

@jasnell Do you still request your suggested changes? 1 & 3 should be fine now, not sure if I should add the Note bit inside the options desc.

[jasnell]

Landed in e1161a3