The GnuPG FAQ is available in plain text from https://gnupg.org/faq/gnupg-faq.txt
This document is in utf-8, however it is served with;

Content-Type: text/plain

which leads to it being interpreted as windows-1252.

The expected value would be:

Content-Type: text/plain; charset=utf-8

You probably want to add a directive like AddDefaultCharset utf-8

Note that this is not specific to text files, for example the HTML version itself is served without a charset as well (and it does include utf-8 characters), albeit browsers are able to pick it from the

<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />

header (I would recommend also adding the charset there, though).