Fix dynamic crates listing in doc sidebar

Author: GuillaumeGomez

src/librustdoc/html/static/main.js

@@ -1447,7 +1447,7 @@
 
         // Draw a convenient sidebar of known crates if we have a listing
         if (rootPath === '../') {
-            var sidebar = document.getElementsByClassName('sidebar')[0];
+            var sidebar = document.getElementsByClassName('sidebar-elems')[0];
             var div = document.createElement('div');
             div.className = 'block crate';
             div.innerHTML = '<h3>Crates</h3>';