doc: txt2pre: modernize and use v5.12

Another teeny step towards v5.12.

diff --git a/Documentation/txt2pre b/Documentation/txt2pre
index 82573a308e7bb9397a23ea1f46d67c9ab937478f..b9d74fb78b1adab9e3544f1d6cc98a66354fa5d1 100755 (executable)
--- a/Documentation/txt2pre
+++ b/Documentation/txt2pre
@@ -1,12 +1,12 @@
-#!/usr/bin/env perl
-# Copyright (C) 2014-2021 all contributors <meta@public-inbox.org>
+#!perl -w
+# n.b. this is invoked via $(PERL) in makefiles
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 #
 # Stupid script to make HTML from preformatted, utf-8 text versions,
 # only generating links for http(s).  Markdown does too much
 # and requires indentation to output preformatted text.
-use strict;
-use warnings;
+use v5.12;
 use PublicInbox::Linkify;
 use PublicInbox::Hval qw(ascii_html);
 my (%xurls, %lei);