[ANN] Specification update

[Stephane Bortzmeyer]

On Tue, Nov 09, 2021 at 08:28:35AM +0000,
 nervuri <nervuri@disroot.org> wrote 
 a message of 9 lines which said:

> > Note that some servers send the TLS proper close for "normal" replies
> > but fail to do so when there is an error, such as 51.
> 
> Molly Brown among them, according to Agunua:

Indeed, see for instance the official site :-(

% agunua gemini.circumlunar.space
# Project Gemini

## Overview
...

% agunua gemini.circumlunar.space/doesnotexist
Warning, no TLS shutdown received from the server
Problem, Not found (extra message: "Not found!").