build: add readthedocs config

.readthedocs.yml

@@ -0,0 +1,19 @@
+# .readthedocs.yml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.8"
+
+python:
+  install:
+    - requirements: requirements/doc.txt