🔧 Add RTD configs and remove GH pages build

.readthedocs.yaml

@@ -0,0 +1,20 @@
+# Configuration on how ReadTheDocs (RTD) builds our documentation
+# ref: https://readthedocs.org/projects/frx-challenges/
+# ref: https://docs.readthedocs.io/en/stable/config-file/v2.html
+#
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+    nodejs: "18"
+  commands:
+    - mkdir $READTHEDOCS_OUTPUT
+    - cd docs
+    - pip install -r requirements.txt
+    - myst build --html --ci --check-links
+    - cp --recursive _build/* $READTHEDOCS_OUTPUT/
+
+# Explicitly opt out of trying to build additional formats such as PDF and ePub
+formats: []