Change naming to "destructible".

docs/contracts/function-modifiers.rst

@@ -39,12 +39,12 @@ if they are marked ``virtual``. For details, please see
         }
     }
 
-    contract retrievable is owned {
+    contract destructible is owned {
         // This contract inherits the `onlyOwner` modifier from
         // `owned` and applies it to the `close` function, which
         // causes that calls to `close` only have an effect if
         // they are made by the stored owner.
-        function close() public onlyOwner {
+        function destroy() public onlyOwner {
             selfdestruct(owner);
         }
     }
@@ -58,7 +58,7 @@ if they are marked ``virtual``. For details, please see
         }
     }
 
-    contract Register is priced, owned {
+    contract Register is priced, destructible {
         mapping (address => bool) registeredAddresses;
         uint price;