update readme

README.md

@@ -3,7 +3,18 @@
 ## How to build demo `quarto.qmd`
 
 1. Build `conda` environment from `environment.yml`.
-1. Run `quarto render`.
+1. Run `quarto render`. This should be very fast.
+
+## How to create PDF
+
+### Setup
+
+1. Install `npm`.
+1. `npm install -g decktape` for global install.
+
+### Repeat
+
+1. `decktape reveal _output/quarto.html _output/quarto.pdf --screenshots-size=1280x720 --fragments=disable` or any other size in px. This takes awhile.
 
 ## TODO