Update versions.html

Updates selector to inlcude 1.7 (rc3).

Author: brianjo

docs/versions.html

@@ -21,7 +21,7 @@ <h1> PyTorch Documentation </h1>
           <a class="reference internal" href="master/">master (unstable)</a>
         </li>
         <li class="toctree-l1">
-          <a class="reference internal" href="1.7.0/">v1.7.0 (rc1)</a>
+          <a class="reference internal" href="1.7.0/">v1.7.0 (rc3)</a>
         </li>
         <li class="toctree-l1">
           <a class="reference internal" href="stable/">v1.6.0 (stable release)</a>