Fix typo in usage instructions.

src/interfaces/python/tutorial/syscat.py

@@ -9,7 +9,7 @@ MODULE SYSCAT.PY : PARSES SOME POSTGRESQL SYSTEM CATALOGS
 This module is designed for being imported from python prompt
 
 In order to run the samples included here, first create a connection
-using :                        cnx = advanced.DB(...)
+using :                        cnx = syscat.DB(...)
 
 The "..." should be replaced with whatever arguments you need to open an 
 existing database.  Usually all you need is the name of the database and,