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

conf.py

@@ -0,0 +1,43 @@
+# Configuration file for the Sphinx documentation builder.
+# Also see the `i18n/` directory.
+#
+# For the full list of built-in configuration values, see the documentation:
+# https://www.sphinx-doc.org/en/master/usage/configuration.html
+
+# -- Project information -----------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
+
+project = 'matrix-docker-ansible-deploy'
+copyright = '2018-%Y, Slavi Pantaleev, Aine Etke, MDAD community members'
+author = 'Slavi Pantaleev, Aine Etke, MDAD community members'
+
+# -- General configuration ---------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
+
+needs_sphinx = '8.1' # For the copyright year placeholder (%Y). Specified with pyproject.toml as well.
+
+extensions = [
+	'myst_parser',
+	'sphinx_markdown_builder'
+]
+myst_gfm_only = True
+myst_heading_anchors = 4 # https://myst-parser.readthedocs.io/en/latest/syntax/optional.html#auto-generated-header-anchors
+
+master_doc = 'README'
+source_suffix = {'.md': 'markdown'}
+
+# Though the default config file advocates exclude_patterns, it is straightforward for us to use include_patterns to select directories explicitly.
+include_patterns = [
+	'docs/*',
+	'i18n/README.md',
+	'*.md',
+]
+
+locale_dirs = ['i18n/locales/']
+gettext_compact = False
+
+# -- Options for HTML output -------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
+
+# html_theme = 'alabaster'
+# html_static_path = ['_static']