Fix static site builder.

utils.md

@@ -5,8 +5,9 @@ Build (approximately) the topic index in the main readme:
 find . -type d -not -path "*/.ipynb_checkpoints" -not -path "*/__pycache__" | sed -En "s|(.*)\/([a-zA-Z0-9'-]*)$|* [\2](\1/\2)|p"
 ```
 
-Build a static html site from all notebooks with their current outputs, using readme as an index page:
+Build a static html site from all notebooks with their current outputs, using readme as an index page (work in progress):
 ```
-pandoc --from markdown --to html README.md -o static/index.html
+mkdir -p static
+sed "s|ipynb|html|" README.md | pandoc --from markdown --to html - -o static/index.html
 find . -type f -name "*.ipynb" | xargs -I {} bash -c 'f="{}" && mkdir -p -- static/"${f%/*}" && jupyter nbconvert --to html $f && mv "${f%.*}.html" static/"${f%/*}"'
 ```