mk docs updated

Author: julitafalcondusza

docs/product_guides/product_guides.md

@@ -16,6 +16,7 @@ Discover the primary ones with the help of product guides. Condensed content all
     "content_management/rich_text/online_editor_guide",
     "content_management/pages/page_builder_guide",
     "content_management/forms/form_builder_guide",
+    "content_management/collaborative_editing/collaborative_editing_guide",
     "customer_management/customer_portal",
     "personalization/personalization_guide",
     "pim/pim_guide",

mkdocs.yml

@@ -282,6 +282,8 @@ nav:
                 - Time field type: content_management/field_types/field_type_reference/timefield.md
                 - URL field type: content_management/field_types/field_type_reference/urlfield.md
                 - User field type: content_management/field_types/field_type_reference/userfield.md
+        - Collaborative editing:
+            - Collaborative editing product guide: content_management/collaborative_editing/collaborative_editing_guide.md
     - Templating:
         - Templating: templating/templating.md
         - Render content: