Update part6b.md

it is not clear what create slice function returns and what the module exports.

Author: amelaku8

src/content/6/en/part6b.md

@@ -512,6 +512,8 @@ const noteSlice = createSlice({
     }
   },
 })
+export const {createNote,toggleImportanceOf} = noteSlice.actions
+export default noteSlice.reducer
 // highlight-end
 ```