Initial work on translations / localization

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3841

Most of the preparation for this was done by Suguru Hirahara (https://github.com/luixxiul).
I've merely reorganized/polished the scripts and instructions in the `i18n/` directory.

While translations can happen even now, more work is necessary to

- make the translation flow better (integrating Weblate), etc.

- restore the Github Actions workflows that Suguru Hirahara had already developed to
  adapt them to our new workflow

i18n/translation-templates/docs/configuring-playbook-nginx.pot

@@ -0,0 +1,25 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) 2018-2024, Slavi Pantaleev, Aine Etke, MDAD community members
+# This file is distributed under the same license as the matrix-docker-ansible-deploy package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: matrix-docker-ansible-deploy \n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2024-12-20 07:23+0200\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#: ../../../docs/configuring-playbook-nginx.md:1
+msgid "Configure Nginx (optional, advanced)"
+msgstr ""
+
+#: ../../../docs/configuring-playbook-nginx.md:3
+msgid "Since 2024-01, this playbook no longer uses nginx as its reverse-proxy."
+msgstr ""