tentative doc update & readthedocs config

Author: vincefn

ObjCryst/doc/.readthedocs.yaml

@@ -0,0 +1,12 @@
+version: 2
+build:
+  os: "ubuntu-22.04"
+  tools:
+    python: "3.12"
+  apt_packages:
+    - doxygen
+    - graphviz
+  jobs:
+    post_build:
+      - cd ObjCryst/doc && doxygen
+      - cp -Rf ObjCryst/doc/build/html/ "$READTHEDOCS_OUTPUT/html/"