modify 'OAuth' tab of login.html to 'External Auth' tab

src/server/views/login.html

@@ -204,7 +204,7 @@
         <hr class="mt-2 mb-0">
         <div class="text-center">
           <button class="collapse-anchor btn btn-xs btn-collapse-oauth mb-3" data-toggle="collapse" data-parent="#accordion" href="#collapse-oauth" aria-expanded="true" aria-controls="collapseOne">
-            OAuth
+            External Auth
           </button>
         </div>
         {% else %}