doc: add note about header values encoding

[ShogunPanda]

This PR add a note about http.Outgoing.setHeader.
At the moment, if the user use .setHeader(name, value) and value contains non latin1 characters, then method will throw an exception. But this is not documented anywhere.

Additionally it also suggests to use RFC8187 standard when UTF-8 values must be passed (rather than arbitrarily convert those values to latin1 as suggested on the net).

Fixes: #42579

[nodejs-github-bot]

Review requested:

• @nodejs/http
• @nodejs/net

[github-actions]

Fast-track has been requested by @ShogunPanda. Please 👍 to approve.

[mcollina]

lgtm

[ShogunPanda]

@aduh95 I see the commit label since this morning. Is the commit queue stuck?

If that's the case I'll land this tomorrow from if you and other collaborators +1 the fast track.

[aduh95]

The commit-queue-squash PRs the Commit Queue should land as one squashed commit. label does not instruct the CQ to land the PR:

node/doc/contributing/commit-queue.md

Lines 40 to 41 in a199387

	To make the Commit Queue squash all the commits of a pull request into the
	first one, add the `commit-queue-squash` label.

Only the commit-queue PRs queued for automated landing through the Commit Queue. label triggers the CQ, so it's not stuck, it simply not on the queue.

node/doc/contributing/commit-queue.md

Lines 18 to 22 in a199387

	From a high-level, the Commit Queue works as follow:
	1. Collaborators will add `commit-queue` label to pull requests ready to land
	2. Every five minutes the queue will do the following for each pull request
	with the label:

You should keep commit-queue-squash PRs the Commit Queue should land as one squashed commit. on this PR otherwise the CQ will refuse to land it (because it contains more than one commit after git rebase --autosquash).

[ShogunPanda]

I see. Actually I was planning to land it manually using git node.

Do you mind approving it so the tool will not complain of commits after latest approvals?

[ShogunPanda]

Landed in dfc2dc8