add missing readthedocs config (unrelated)

Author: hoehnp

.readthedocs.yaml

@@ -0,0 +1,21 @@
+# Read the Docs configuration file for Sphinx projects
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+version: 2
+
+build:
+  os: "ubuntu-22.04"
+  tools:
+    python: "3.12"
+
+# Build from the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+# Explicitly set the version of Python and its requirements
+python:
+  install:
+    - requirements: docs/requirements.txt
+
+formats: all
+