updated build book to base off production branch

Author: trevorcampbell

.github/workflows/build_book.yml

@@ -2,7 +2,7 @@ name: Rebuild and deploy book to gh-pages branch
 on:
   push:
     branches:
-      - main
+      - production
     paths:
       - source/**
 
@@ -17,7 +17,7 @@ jobs:
       - name: checkout
         uses: actions/checkout@v2
         with:
-          ref: 'main'
+          ref: 'production'
 
       - name: Build the book
         run: |