Remove obsolete comment.

ON CONFLICT (xxx) DO NOTHING is natively supported by sqlite.

https://sqlite.org/lang_upsert.html

Author: guiguid

examples/user-authentication/create_user.sql

@@ -1,10 +1,10 @@
 INSERT INTO user_info (username, password_hash)
 VALUES (:username, sqlpage.hash_password(:password))
-ON CONFLICT (username) DO NOTHING -- this syntax is PostgreSQL-specific. In SQLite, use ON CONFLICT IGNORE.
+ON CONFLICT (username) DO NOTHING
 RETURNING 
     'redirect' AS component,
     'create_user_welcome_message.sql?username=' || :username AS link;
 
 -- If we are still here, it means that the user was not created
 -- because the username was already taken.
-SELECT 'redirect' AS component, 'create_user_welcome_message.sql?error&username=' || :username AS link;
+SELECT 'redirect' AS component, 'create_user_welcome_message.sql?error&username=' || :username AS link;