I haven't seen the contract between Peel and Everton, no. lol
But, it was definitely reported in one of those construction industry reports that were published online (and shared here) when the deal was signed. Pretty sure it was covered by the echo too, but finding anything on that wretched website with all the pop-ups isn't worth the arseache.
It stated that The Stadium and surrounding land must remain under the Everton Stadium Company Ltd, which in turn must remain under the full ownership of Everton Football Club.