Fix a <cxx-ref> to observer_ptr.

Author: jyasskin

general.html

@@ -209,7 +209,7 @@ <h1>Feature-testing recommendations (Informative)</h1>
         <tr>
           <td>N4282</td>
           <td>The World’s Dumbest Smart Pointer</th>
-          <td><cxx-ref to="memory.observer_ptr"></cxx-ref></th>
+          <td><cxx-ref to="memory.observer.ptr"></cxx-ref></th>
           <td><code>observer_ptr</code></th>
           <td>201411</th>
           <td><code>&lt;experimental/memory></code></th>