Edit dbforge drop_table line 230

At current the documentation does not distinguish between DROP TABLE IF EXISTS table_name and DROP TABLE table_name. As seen by the DB_forge.php class in system/database; the function accepts a Boolean as the second parameter as to whether or not to apply the IF EXISTS mysql condition.
diff --git a/user_guide_src/source/database/forge.rst b/user_guide_src/source/database/forge.rst
index 89fac02..a4edada 100644
--- a/user_guide_src/source/database/forge.rst
+++ b/user_guide_src/source/database/forge.rst
@@ -227,7 +227,7 @@
 	$this->dbforge->drop_table('table_name');
 
 	// Produces: DROP TABLE IF EXISTS table_name
-	$this->dbforge->drop_table('table_name');
+	$this->dbforge->drop_table('table_name',TRUE);
 
 
 Renaming a table
@@ -405,4 +405,4 @@
 		:returns:	TRUE on success, FALSE on failure
 		:rtype:	bool
 
-		Renames a table. Usage:  See `Renaming a table`_.
\ No newline at end of file
+		Renames a table. Usage:  See `Renaming a table`_.