Added simple executable for rendering rst files.

Dockerfile

@@ -0,0 +1,4 @@
+FROM gitea/gitea:latest
+COPY ./rst2htmlbody.py /bin/rst2htmlbody
+RUN apk --no-cache add py3-docutils && \
+    chmod 755 /bin/rst2htmlbody

README.rst

@@ -0,0 +1,42 @@
+Restructured text renderer for Gitea
+====================================
+
+This is simple custom rst2html5 renderer for `Gitea`_.
+
+Installation
+------------
+
+Before starting deployment of Gitea using docker or docker-compose, you'll
+need to create an altered image which would contain `docutils`_ python package.
+There is a simple Dockerfile attached, which can be adjusted to your needs
+(i.e. it might be needed to pin to stable version of gitea), than let's assume,
+that we tag the image with ``:rst``:
+
+.. code:: shell
+
+   $ docker build -t gitea:rst -f Dockerfile .
+
+Procedure of running dockerized deployment is `same as documented`_.
+
+Now, as you have it up and running, there is still a need for altering
+configuration. Stop the container, and alter file
+``path-to/gitea/conf/app.ini``, and add external renderer section:
+
+.. code:: ini
+
+   [markup.restructuredtext]
+   ENABLED = true
+   FILE_EXTENSIONS = .rst
+   RENDER_COMMAND = "rst2htmlbody"
+   IS_INPUT_FILE = false
+
+
+And that's it!
+
+Unfortunately, you'll need to repeat those steps every time you'd like to
+update gitea.
+
+
+.. _docutils: https://docutils.sourceforge.io
+.. _gitea: https://gitea.io
+.. _same as documented: https://docs.gitea.io/en-us/install-with-docker/

rst2htmlbody.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+import sys
+
+from docutils import core
+from docutils.writers import html5_polyglot
+
+
+def main():
+    if not sys.stdin.isatty():
+        text = sys.stdin.readlines()
+    else:
+        if len(sys.argv) != 2:
+            print("There is no piped reSt source nor provided file, abort.")
+            sys.exit(4)
+        with open(sys.argv[1]) as fobj:
+            text = fobj.read()
+
+    parts = core.publish_parts(writer=html5_polyglot.Writer(),
+                               source=''.join(text))
+
+    print(parts.get('body', ''))
+
+
+if __name__ == '__main__':
+    main()