Fix the built docs dir path in the tip

Author: webknjaz

tox.ini

@@ -83,7 +83,7 @@ commands =
   # Print out the output docs dir and a way to serve html:
   -{envpython} -c\
   'import pathlib;\
-  docs_dir = pathlib.Path(r"{toxworkdir}") / "docs_out";\
+  docs_dir = pathlib.Path(r"{envdir}") / "docs_out";\
   index_file = docs_dir / "index.html";\
   print(f"\nDocumentation available under\
   `file://\{index_file\}`\n\nTo serve docs, use\