Addition of "doctype"/datatype as another possible facet and search element to use

src/components/active-facet-category/ActiveFacetCategory.ts

@@ -34,6 +34,8 @@ export default class ActiveFacetCategory extends Vue {
                 return "creator";
             case "subjects":
                 return "keyword";
+            case "doctype":
+                    return "datatype";
             default:
                 return this.categoryName;
         }