Add validation step for Jupyter Book source

Added a step to validate Jupyter Book source before building.

Author: Hem-W

.github/workflows/book.yml

@@ -23,6 +23,11 @@ jobs:
       run: |
         pip install -r requirements.txt
 
+        
+    - name: Validate Jupyter Book Source
+      run: |
+        pwd
+        jupyter-book config validate .
 
     # Build the book
     - name: Build the book