Fix typo in product category procedure (#353)

Author: dabrt

docs/pim/work_with_product_categories.md

@@ -82,7 +82,7 @@ You can create or change product category relationships with products in two way
 1. In the left panel, click **Product catalog** -> **Products** to navigate to the product list.
 2. To create a new product item, click the  **Create** button, select the product types with product categories enabled, and click **Add**. Then skip to step 4.
 3. To edit an existing product item, click the **Edit** icon next to a name of the Product item that you want to modify.
-4. In the product type editing modal, go to the **Product category** area and click the **Select product categories** button.
+4. In the product editing modal, go to the **Product category** area and click the **Select product categories** button.
 5. In the pop-up window, select checkboxes next to product categories related with the product.
 6. Click **Select** to close the pop-up window.
 7. Optionally, modify other product information as required.