MapboxVectorTileCatalogItem: move JSDoc

Putting the JSDoc after the decorator
but before the rest of the declaration
confuses more recent versions of
Prettier, and possibly other tools as
well. Move the decorator next to
the declaration.

lib/Models/Catalog/CatalogItems/MapboxVectorTileCatalogItem.ts

@@ -146,11 +146,11 @@ class MapboxVectorTileCatalogItem extends MappableMixin(
     }
   }
 
-  @computed
   /** Convert traits into paint rules:
    * - `layer` and `fillColor`/`lineColor` into simple rules
    * - `parsedJsonStyle`
    */
+  @computed
   get paintRules(): PaintRule[] {
     const rules: PaintRule[] = [];