add conf.py path

Author: Juan Orduz

.readthedocs.yaml

@@ -1,6 +1,9 @@
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
 version: 2
+sphinx:
+  # Path to your Sphinx configuration file.
+  configuration: docs/conf.py
 
 build:
   os: ubuntu-20.04