removed nb dir from git tracking

nb/script1.sh

@@ -1,8 +0,0 @@
-#!/bin/bash
-cp ../chapters/*.quarto_ipynb .
-for i in *.quarto_ipynb 
-    do
-      echo $i
-      mv $i "${i%.quarto_ipynb}.ipynb"
-      jupyter nbconvert --inplace --clear-output --to notebook "${i%.quarto_ipynb}.ipynb"
-    done