mobx-6 migration -- part 1

Signed-off-by: Roman <ixrock@gmail.com>

docs/extensions/guides/stores.md

@@ -51,8 +51,6 @@ export class ExamplePreferencesStore extends Store.ExtensionStore<ExamplePrefere
   toJSON(): ExamplePreferencesModel {
     return toJS({
       enabled: this.enabled
-    }, {
-      recurseEverything: true
     });
   }
 }