Fix text overflow in sidebar (#1184)

Co-authored-by: c4710n <c4710n@users.noreply.github.com>

Author: c4710n

assets/less/sidebar.less

@@ -227,6 +227,8 @@
       padding: 0;
       line-height: 27px;
       white-space: nowrap;
+      overflow: hidden;
+      text-overflow: ellipsis;
 
       &.open > ul {
         display: block;