update Readme with rendering instructions

README.md

@@ -1,3 +1,9 @@
 A utility repository to build a quarto book website for the BMM Developer Notes for the bmm package: https://github.com/venpopov/bmm
 
-The contents of the `_book` directory contain the rendered website, and they are automatically pushed via Github Action to the gh-pages branch of `bmm`
+The contents of the `_book` directory contain the rendered website, and they are automatically pushed via Github Action to the gh-pages branch of `bmm`.
+
+## How to makes changes
+
+1. Make the changes to the .qmd files
+2. Run `quarto render` from the terminal to render the book
+3. Commit and push the changes to the `master` branch