fix(mongodb): create user

Author: ldecarvalho-doc

pages/managed-mongodb-databases/how-to/manage-users.mdx

@@ -40,6 +40,38 @@ You can create more users and grant them pre-set roles via the [Scaleway Managed
   All users you create have at first administrator roles, which can be changed after creation with the [Apply user roles](https://www.scaleway.com/en/developers/api/managed-database-mongodb/#path-users-apply-user-roles) call. The default user's role cannot be changed.
 </Message>
 
+### How to create a user
 
+1. Edit the POST request payload you will use to create your user. Replace the values of each parameters with your values of choice following the parameter descriptions below.
+    ```
+      {
+        "name": "<username>",
+        "password": "<password>",
+      }
+    ```
+
+    | Parameter        | Description                                                        |
+    | :--------------- | :----------------------------------------------------------------- |
+    | `name`     | Set a name for the database user. |
+    | `password`           | Set a password for the database user.|
+
+2. Run the following command to create a user. Make sure you include the payload you edited in the previous step.
+    ```
+    curl -X POST \
+      -H "X-Auth-Token: $SCW_SECRET_KEY" \
+      -H "Content-Type: application/json" \
+      -d '{
+        "name": "<username>",
+        "password": "<password>",
+        "roles": [
+            {
+                "role": "string",
+                "database": "string",
+                "any_database": true
+            }
+        ]
+    }' \
+      "https://api.scaleway.com/mongodb/v1alpha1/regions/fr-par/instances/{instance_id}/users"
+    ```