Update .readthedocs.yaml

.readthedocs.yaml

@@ -10,20 +10,16 @@ build:
   os: ubuntu-20.04
   tools:
     python: "3.9"
-    # You can also specify other tool versions:
-    # nodejs: "16"
-    # rust: "1.55"
-    # golang: "1.17"
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
    configuration: docs/conf.py
 
 # If using Sphinx, optionally build your docs in additional formats such as PDF
-# formats:
-#    - pdf
+formats:
+   - pdf
 
 # Optionally declare the Python requirements required to build your docs
 python:
    install:
-   - requirements: docs/requirements.txt
+   - requirements: requirements/docs.txt