scripts: Updated validation_stats error output

Change-Id: I41f592c8fa7a9180d5bd07446d965fa9eb287558
diff --git a/scripts/vk_validation_stats.py b/scripts/vk_validation_stats.py
index 7db6739..3c930f3 100755
--- a/scripts/vk_validation_stats.py
+++ b/scripts/vk_validation_stats.py
@@ -186,8 +186,9 @@
                         qualified_paths.append(filepath)
                         continue
             if len(self.generated_source_files) != len(qualified_paths):
-                print("Error: Unable to locate one or more of the following source files in the build, dbuild, or release directories")
+                print("Error: Unable to locate one or more of the following source files in the %s directories" % (", ".join(generated_source_directories)))
                 print(self.generated_source_files)
+                print("Skipping documentation validation test")
                 quit()
             else:
                 self.source_files.extend(qualified_paths)