ci: add Read the Docs config

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: FBumann

.readthedocs.yaml

@@ -0,0 +1,16 @@
+version: 2
+
+mkdocs:
+  configuration: mkdocs.yml
+
+build:
+  os: ubuntu-24.04
+  tools:
+    python: "3.13"
+
+python:
+  install:
+    - method: pip
+      path: .
+      extra_requirements:
+        - docs