Revert "Hide docs sidebar scrollbar by default"

docs/style.css

@@ -117,14 +117,3 @@ h6 code:not(pre code) {
   background: #334155;
   border: 1px solid #64748b;
 }
-
-/* Hide the sidebar overflow by default, but allow it to be shown on hover */
-#sidebar-content {
-  overflow-y: hidden;
-}
-
-#sidebar-content:hover,
-#sidebar-content:active,
-#sidebar-content:focus {
-  overflow-y: auto;
-}