[TASK] document how to migrate to rst (#479)

* [TASK] document how to migrate to rst

* Update MarkdownToReST.rst

---------

Co-authored-by: Lina Wolf <48202465+linawolf@users.noreply.github.com>

Documentation/Howto/Migration/Index.rst

@@ -414,3 +414,9 @@ The current recommendation is to only remove the :file:`genindex.rst` file
 from your documentation directory, but keep all the placed `..  index`
 directives. If at some point the automatic index generation is re-introduced,
 your old indexes will be able to show up again.
+
+..  toctree::
+    :hidden:
+    :glob:
+
+    *

Documentation/Howto/Migration/MarkdownToReST.rst

@@ -0,0 +1,67 @@
+:navigation-title: Markdown to ReST
+
+..  include:: /Includes.rst.txt
+..  index::
+    Documentation; Migration
+    docs.typo3.org
+..  _migrate-markdown-to-rest:
+
+=============================================
+Migration: Markdown to reStructuredText (ReST)
+=============================================
+
+Markdown is very popular and widely used for documentation. However, ReST is more powerful and flexible.
+The TYPO3 documentation toolchain contains a lot of features that are only available with ReST.
+Because of the extendability of ReST. This guide explains how to migrate Markdown files to ReST,
+using the TYPO3 documentation toolchain.
+
+Unless you have a specific reason to migrate to ReST, it is perfectly fine to keep using Markdown.
+The TYPO3 documentation toolchain supports both formats.
+
+..  note::
+
+    This guide assumes you have already set up the TYPO3 documentation toolchain.
+    If you haven't, please follow the instructions in the :ref:`rendering-docs` guide.
+
+..  _migrate-markdown-to-rest-conversion:
+
+Converting Markdown to ReST
+===========================
+
+The first step is to convert the Markdown files to ReST. This can be done using
+our rendering toolchain. This will convert the Markdown files to ReST format.
+We will use ``Documentation-Migrated`` as the output directory.
+
+..  tabs::
+
+    ..  group-tab:: Linux
+
+        ..  code-block:: bash
+
+            mkdir -p Documentation-Migrated
+            docker run --rm --pull always -v $(pwd):/project -it ghcr.io/typo3-documentation/render-guides:latest --theme=rst --output-format=rst --output Documentation-Migrated
+
+    .. group-tab:: MacOS
+
+        ..  code-block:: bash
+
+            mkdir -p Documentation-Migrated
+            docker run --rm --pull always -v $(pwd):/project -it ghcr.io/typo3-documentation/render-guides:latest --theme=rst --output-format=rst --output Documentation-Migrated
+
+    ..  group-tab:: Windows
+
+        ..  code-block:: powershell
+
+            New-Item -ItemType Directory -Force -Path ".\Documentation-Migrated"
+            docker run --rm --pull always -v ${PWD}:/project -it ghcr.io/typo3-documentation/render-guides:latest --theme=rst --output-format=rst --output Documentation-Migrated
+
+Now we can copy the ``guides.xml`` from the original directory documentation directory to the new directory. And remove the
+option ``input-format="md"``. This will tell the rendering toolchain to use the ReST files instead of the Markdown files.
+
+Last step is to swap the directories. Rename the original directory to ``Documentation-Markdown`` and the new directory ``Documentation-Migrated`` to ``Documentation``.
+
+The basic migration is now done. Some manual adjustments might be necessary, as the conversion is not perfect.
+
+..  tip::
+
+    If you notice any issues with the conversion, please report them to the :ref:`TYPO3 documentation team <contact-us>`.