remove 'optional gc' from the homepage

Gc<T> is neither real, nor a GC, nor a good idea.

Author: steveklabnik

index.html

@@ -38,7 +38,6 @@ <h2>Featuring</h2>
         <li>type inference</li>
         <li>zero-cost abstractions</li>
         <li>guaranteed memory safety</li>
-        <li>optional garbage collection</li>
         <li>concurrency without data races</li>
         <li>minimal runtime</li>
         <li>efficient C bindings</li>
@@ -175,4 +174,4 @@ <h2>Featuring</h2>
     .ace-chrome .ace_string {
         color: #3E999F;
     }
-  </style>
+  </style>