Add explicit readthedocs configuration

Author: mbeijen

.readthedocs.yaml

@@ -0,0 +1,15 @@
+version: 2
+
+build:
+  os: ubuntu-20.04
+  tools:
+    python: "3.10"
+
+python:
+  install:
+    - method: pip
+      path: .
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+   configuration: docs/conf.py