refactor: cleanup unused state

Author: Dobromir Hristov

src/components/DocumentationTopic.vue

@@ -140,7 +140,7 @@ export default {
       default() {
         return {
           reset() {},
-          state: { onThisPageSections: [] },
+          state: {},
         };
       },
     },
@@ -314,9 +314,6 @@ export default {
         0,
       );
     },
-    onThisPageSections() {
-      return this.topicState.onThisPageSections;
-    },
     hasAvailability: ({ platforms, technologies }) => (
       (platforms || []).length || (technologies || []).length
     ),