The first link in the search result on http://www.oracle.com/pls/db112/homepage for the parameter "STATISTICS_LEVEL" leads me to the STAR_TRANSFORMATION_ENABLED parameter page in Database Reference (http://docs.oracle.com/cd/E11882_01/server.112/e25513/initparams251.htm).
Thank you for pointing out this problem. It has been fixed. (If you still see the wrong topic being linked to, try refreshing your browser. If it's still a problem, it might take a little while for the Database 11.2 documentation library to be updated on various systems worldwide. It did work just now for me.)