diff --git a/ecoval/__init__.py b/ecoval/__init__.py
index 95f54ac..3dcfff5 100755
--- a/ecoval/__init__.py
+++ b/ecoval/__init__.py
@@ -999,6 +999,7 @@ def make_header_bold(x):
 def rebuild(build = None):
     """
     This function will rebuild the book.
+    Use this if you have modified the notebooks generated and want to create a validation report.
 
     Parameters
     ----------