improve readthedocs config

.readthedocs.yaml

@@ -3,4 +3,13 @@ version: 2
 build:
   os: "ubuntu-20.04"
   tools:
-    python: "3.8"
+    python: "3.8"
+
+sphinx:
+  fail_on_warning: true
+
+python:
+  # Install our python package before building the docs
+  install:
+    - method: pip
+      path: .