docs/guide/catalog/*.md: Fix links

Author: adriendupuis

docs/guide/catalog/product.md

@@ -12,7 +12,7 @@ The built-in Product Content Type contains the following Fields:
 |Long description | `ses_long_description` | `ezrichtext` | Long product description  |
 |Specifications | `ses_specifications` | `sesspecificationstype` | A set of product specification values. They are indexed in the search engine and can be used for faceted search |
 |EAN | `ses_ean` | `ezstring` | European Article Number |
-|Variants | `ses_variants` | `uivarvarianttype` | [Product variants](#product-variants) |
+|Variants | `ses_variants` | `uivarvarianttype` | [Product variants](product_variants.md) |
 |Manufacturer SKU | `ses_manufacturer_sku` | `ezstring` | SKU of the product  as assigned by the manufacturer |
 |Unit price | `ses_unit_price` | `ezstring` | Product price |
 |Product image | `ses_image_main` | ezimage | Main product image |

docs/guide/catalog/product_variants/setting_up_variants_from_external_source.md

@@ -7,11 +7,11 @@ You can set the variants up by [using a variant Field Type](product_variants.md)
 You can also set up variants if you are not using the default Content Types
 and don't want to set up variants manually in the Back Office.
 
-To do this, you need to map your variant structure to the [`VariantProductNode`](product_variants.md#variantproductsnode) structure.
+To do this, you need to map your variant structure to the [`VariantProductNode`](product_variant_api.md#variantproductnode) structure.
 
 !!! tip
 
-    The main job of every catalog factory is to fill the [`VariantProductNode`](product_variants.md#variantproductsnode) attribute `variantCharacteristics`.
+    The main job of every catalog factory is to fill the [`VariantProductNode`](product_variant_api.md#variantproductnode) attribute `variantCharacteristics`.
     The basic concept is to take information from the provided `dataMap`
     (e.g. coming from the data provider, either from the content model or from an external source)
     and create an attribute `variantCharacteristic` for the `VariantProductNode`.