Move requirements into their own directory

.buildkite/test-pipeline.yaml

@@ -35,7 +35,7 @@ steps:
   fast_check: true
   no_gpu: True
   commands:
-  - pip install -r requirements-docs.txt
+  - pip install -r requirements/docs.txt
   - SPHINXOPTS=\"-W\" make html
   # Check API reference (if it fails, you may have missing mock imports)
   - grep \"sig sig-object py\" build/html/api/inference_params.html

.readthedocs.yaml

@@ -18,4 +18,4 @@ formats: []
 # Optionally declare the Python requirements required to build your docs
 python:
   install:
-    - requirements: docs/requirements-docs.txt
+    - requirements: requirements/docs.txt

docs/README.md

@@ -4,7 +4,7 @@
 
 ```bash
 # Install dependencies.
-pip install -r requirements-docs.txt
+pip install -r ../requirements/docs.txt
 
 # Build the docs.
 make clean