Update description

Co-authored-by: Adam Turner <[email protected]>

Author: hugovk

build_docs.py

@@ -26,7 +26,7 @@
 ```
 
 Languages are stored in `config.toml` while versions are discovered
-from the PEPs site.
+from peps.python.org (generated by `python-releases.toml`).
 
 -q selects "quick build", which means to build only HTML.