Merge pull request #314 from swan-io/DOC-771/sandbox-user-hint

Doc 771/sandbox user hint

Author: ntombing

docs/topics/users/identifications/sandbox.mdx

@@ -7,6 +7,7 @@ title: Sandbox
 :::info Sandbox users
 You can create, update, endorse, and delete Sandbox users with the Testing API.
 Refer to the [example mutations](../../../developers/tools/sandbox-users.mdx#examples) on the **Sandbox users** page.
+You can only simulate an identification on [Sandbox users](../../../developers/tools/sandbox-users.mdx#overview) who are linked to your project.
 :::
 
 ## Simulate creating an identification {#simulate-create}