Add renderer for Sphinx .rst files, for user manual previews

Ref infrastructure/blender-projects-platform#51

Pull Request: https://projects.blender.org/infrastructure/gitea-custom/pulls/2

sphinx/template/conf.py

@@ -0,0 +1,22 @@
+# Configuration file for RST preview.
+
+import os
+import sys
+
+# Extensions
+sys.path.append(os.path.abspath('exts'))
+extensions = [
+    'reference',
+    'peertube',
+    'sphinx.ext.mathjax',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.todo',
+]
+
+# Project
+project = 'projects.blender.org'
+root_doc = 'contents'
+
+# Theme: epub hides all navigation, sidebars, footers.
+html_theme = 'epub'
+html_permalinks = False