refactor: remove forum and topic feature chains

assets/css/routes/docs.css

@@ -8,7 +8,6 @@
 @import url("docs/depth-based-indentation.css");
 @import url("docs/collapsible-state.css");
 @import url("docs/active-item-highlight-bar.css");
-@import url("docs/special-page-grid.css");
-@import url("docs/special-cover-enhancements.css");
+@import url("docs/toolbar-search-enhancements.css");
 @import url("docs/pagination-inside-search-results.css");
 @import url("docs/empty-state-enhancement.css");