docs: update description

Author: kenjis

user_guide_src/source/database/transactions.rst

@@ -61,12 +61,16 @@ Strict Mode can be disabled as follows:
 Managing Errors
 ===============
 
-If you have error reporting enabled in your Config/Database.php file
-you'll see a standard error message if the commit was unsuccessful. If
-debugging is turned off, you can manage your own errors like this:
+If you have ``DBDebug`` true in your **app/Config/Database.php** file
+you'll see an exception thrown if the commit was unsuccessful. If
+``DBDebug`` is false, you can manage your own errors like this:
 
 .. literalinclude:: transactions/003.php
 
+.. note:: Since v4.3.0, ``DBDebug`` is true by default. In previous versions,
+    it was false in production environment, and different database drivers might
+    throw different exception classes or did not throw exceptions.
+
 Disabling Transactions
 ======================