Switch the readthedoc build to Nix

.readthedocs.yaml

@@ -15,15 +15,8 @@ build:
     pre_install:
       - mkdir -p ~/.nix ~/.config/nix
       - echo "experimental-features = nix-command flakes" > ~/.config/nix/nix.conf
-      - proot -b ~/.nix:/nix /bin/sh -c "nix build -L .#optionsDoc && cp -v result docs/options.md"
-
-sphinx:
-   configuration: docs/conf.py
-
-formats:
-  - pdf
-  - epub
-
-python:
-   install:
-   - requirements: docs/requirements.txt
+    build:
+      html:
+        - proot -b ~/.nix:/nix /bin/sh -c "pwd"
+        - proot -b ~/.nix:/nix /bin/sh -c "ls -l ./"
+        - proot -b ~/.nix:/nix /bin/sh -c "nix build -L .#documentation && cp -rv result $READTHEDOCS_OUTPUT/html/"

docs/requirements.txt

@@ -1,4 +0,0 @@
-sphinx ~= 5.3
-sphinx_rtd_theme ~= 1.1
-myst-parser ~= 0.18
-linkify-it-py ~= 2.0