bug #12618 [Docs] Fix cookbook for custom entity (Tomanhez)

This PR was merged into the 1.9 branch.

Discussion
----------

| Q               | A
| --------------- | -----
| Branch?         | master
| Bug fix?        | yes
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| License         | MIT

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Commits
-------

ba9c52f Fix entity guide

docs/cookbook/entities/custom-model.rst

@@ -180,7 +180,6 @@ Having a grid prepared we can configure routing for the entity administration:
         resource: |
             alias: app.supplier
             section: admin
-            path: admin
             templates: "@SyliusAdmin\\Crud"
             redirect: update
             grid: app_admin_supplier
@@ -190,28 +189,8 @@ Having a grid prepared we can configure routing for the entity administration:
                 index:
                     icon: 'file image outline'
         type: sylius.resource
+        prefix: /admin
 
-.. note::
-
-    You can replace ``path: admin`` with ``prefix: /admin``
-
-    .. code-block:: yaml
-
-        # config/routes.yaml
-        app_admin_supplier:
-            resource: |
-                alias: app.supplier
-                section: admin
-                templates: "@SyliusAdmin\\Crud"
-                redirect: update
-                grid: app_admin_supplier
-                vars:
-                    all:
-                        subheader: app.ui.supplier
-                    index:
-                        icon: 'file image outline'
-            type: sylius.resource
-            prefix: /admin
 
 10. Add entity administration to the admin menu
 -----------------------------------------------