[ci skip] Remove an assign-by-ref example from DButil docs

Triggers an E_DEPRECATED message; reported via the forums:
http://forum.codeigniter.com/thread-62178-post-319791.html
diff --git a/user_guide_src/source/database/utilities.rst b/user_guide_src/source/database/utilities.rst
index 81b949d..2fa5239 100644
--- a/user_guide_src/source/database/utilities.rst
+++ b/user_guide_src/source/database/utilities.rst
@@ -180,7 +180,7 @@
 
 .. note:: For Interbase/Firebird databases, the backup file name is the only parameter.
 
-		Eg. $this->dbutil->backup('db_backup_filename');
+		$this->dbutil->backup('db_backup_filename');
 
 .. note:: Due to the limited execution time and memory available to PHP,
 	backing up very large databases may not be possible. If your database is
@@ -197,7 +197,7 @@
 	$this->load->dbutil();
 
 	// Backup your entire database and assign it to a variable
-	$backup =& $this->dbutil->backup();
+	$backup = $this->dbutil->backup();
 
 	// Load the file helper and write the file to your server
 	$this->load->helper('file');