Documenting OutgoingMessage

[caleblallen]

I took a crack at Documenting Outgoing Message per #33847

Repeated and cleaned up language from http.ServerResponse.

I cannot figure out how to get OutgoingMessage to send on its own, however. It feels like it is intended as an abstract class for http.ServerResponse?

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[kaizhu256]

note http.OutgoingMessage is also inherited by http.ClientRequest. the example below illustrates its usage in both client and server.

let http = require("http");

// OutgoingMessage used in http-client
let outgoingMessage1 = http.request("http://www.example.com", console.log);
outgoingMessage1.end("upload some data");

// OutgoingMessage used in http-server
http.createServer(function (req, outgoingMessage2) {
    outgoingMessage2.statusCode = 404;
    outgoingMessage2.end("404 Not Found");
}).listen(8080);